だけでなく・
Choosing among ways to say “not only”
The best choice depends less on the English words “not only” than on the relationship between A and B. Ask whether B is simply another fact, an extension beyond an obvious baseline, a stronger surprise, an added factor, or the main point you want to spotlight. Register then narrows the choice further.
Start with the relationship between A and B
All these constructions add B after A, but they do not organize that addition in the same way. The added part often contains も, though the particle required by the sentence may differ. Keep A and B connected by one clear larger point: two benefits, two problems, two affected groups, or two reasons for the same evaluation.
A practical decision map
Choose the relationship first, then choose the level of formality.
Flat, neutral addition
だけでなく or ばかりでなく
B is simply another relevant fact. The first is the everyday default; the second is somewhat more formal and suits careful explanation.
Neither form requires B to be surprising.
An obvious baseline
はもちろん or はもとより
A goes without saying and B extends the claim beyond it. The first works in ordinary speech and writing; the second belongs mainly to formal writing and prepared speech.
A must genuinely be easy for the listener or reader to accept.
Formal flat addition
のみならず
You need a formal equivalent in a report, essay, public statement, or prepared speech.
It usually sounds deliberately stiff in relaxed conversation.
A stronger or surprising B
ばかりか
B raises the force of the statement by being stronger, worse, better, or more remarkable than A.
Escalation is a strong natural tendency, not an absolute rule, but this is not the safest choice for a flat list.
Facts or factors accumulating
上（に） or に加えて
You are stacking reasons, qualities, costs, requirements, or other factors. The first readily follows a verb or adjective; the second is more analytical and often follows a noun.
The clearest examples point in the same direction, though mixed facts are possible when they still support one coherent conclusion.
A rhetorical scale or shift of attention
はおろか or もさることながら
Use the first for a sharp “let alone” scale. Use the second to acknowledge A as important and then give B greater attention.
The second form does not reject A.
The same flat addition at three register levels
A policy simplifies the application process and shortens waiting times; neither benefit is presented as surprising.
この制度は手続きを簡単にするだけでなく、待ち時間も短くする。
This system not only simplifies the procedure but also shortens waiting times.
Analyzeこの制度は手続きを簡単にするばかりでなく、待ち時間も短くする。
This system not only simplifies the procedure but also shortens waiting times.
AnalyzeThis version sounds more like a careful explanation.
本制度は手続きを簡素化するのみならず、待ち時間も短縮する。
This system not only streamlines procedures but also reduces waiting times.
AnalyzeThis wording fits a report, policy document, or prepared public statement.
Takeaway: The facts stay essentially the same. What changes is the level of formality: everyday, careful, then distinctly formal.
An accepted baseline is not the same as escalation
はもちろん and はもとより present A as expected or already granted. By contrast, ばかりか makes the movement toward B more forceful. With the baseline forms, ask whether A truly goes without saying; with the escalating form, ask whether B deserves extra weight.
Stacking a quality or adding a separate factor
上（に） is natural when one clause gives a quality or circumstance and the next adds another layer. に加えて often sounds more analytical, especially with noun-based factors in reports, plans, meetings, and presentations.
Two advanced forms with opposite treatment of A
The speaker wants more than a neutral addition: either a sharp scale or a deliberate shift of attention.
彼は専門書はおろか、短い記事さえ読もうとしない。
He will not even try to read a short article, let alone a specialist book.
AnalyzeThe harder case comes first in Japanese; the more basic failure follows.
この店は料理の味もさることながら、客への細やかな気配りも評価されている。
The restaurant is praised for the taste of its food, but also, and especially, for its thoughtful attention to customers.
AnalyzeThe food genuinely deserves praise; the service receives the stronger spotlight.
Takeaway: The first form treats A as already beyond reach before extending the statement to B. The second explicitly grants the importance of A before redirecting attention toward B.
More examples across the family
この公園は春だけでなく、秋も花が楽しめる。
In this park, flowers can be enjoyed not only in spring but also in autumn.
Analyzeこの提案は費用を抑えるばかりでなく、作業時間も短縮する。
This proposal not only keeps costs down but also reduces working time.
Analyze物理学の教授である彼女は、基礎理論はもちろん、最新の研究動向にも詳しい。
As a physics professor, she knows not only the basic theory, as expected, but also the latest research trends.
Analyze本事業は都市部のみならず、農村部にも雇用を生み出す。
This project creates employment not only in urban areas but also in rural areas.
Analyze大雨は道路を冠水させたばかりか、橋まで損傷させた。
The heavy rain not only flooded roads but even damaged a bridge.
Analyze本規則は正社員はもとより、契約社員にも適用される。
These rules apply not only to permanent employees, as expected, but also to contract employees.
Analyzeこの靴は軽い上に、雨にも強い。
These shoes are light and, on top of that, resistant to rain.
Analyze人口減少に加えて、公共交通の縮小も課題だ。
In addition to population decline, the reduction of public transportation is also a challenge.
Analyze彼は報告書はおろか、メモさえ提出しなかった。
He did not even submit a memo, let alone a report.
Analyzeこの小説は物語の構成もさることながら、会話の自然さも魅力だ。
The novel’s plot construction is impressive, but the natural dialogue is also a major attraction.
Analyze