がてらWhile out doing; taking the opportunity to
This construction presents one outing or activity as the occasion for carrying out an additional purpose. The same person performs both actions as part of one occasion.
How the two actions fit together
がてら does more than say that two actions happen at the same time. The activity before it establishes the outing or occasion, and the following action gives an added purpose. Both actions are normally performed by the same person during that one occasion.
Noun and verb forms
The first example uses an action noun; the second uses a verb stem.
私は散歩がてら、図書館に予約した本を受け取りに行った。
While out for a walk, I went to the library to pick up a book I had reserved.
AnalyzeThe walk creates the occasion for the trip to the library.
祖父は町の様子を見がてら、昔の知人を訪ねた。
Grandfather visited an old acquaintance while taking the opportunity to see how the town was doing.
Analyze見がてら is formed from the stem of 見ます.
Activities that work naturally
The activity before the construction should naturally create the opportunity needed for what follows. Outings such as 散歩, 買い物, 運動, and 花見 are therefore particularly common and easy to use naturally.
One outing, two purposes
姉は書類を届けがてら、以前の同僚に挨拶してきた。
My sister delivered some documents and used the occasion to greet her former colleagues.
AnalyzeLiterally: My sister, while going to deliver documents, went and greeted her former colleagues.
Choosing among similar constructions
ついでに is the more flexible everyday choice for doing something incidental while the opportunity is available. がてら is narrower and more marked, often organizing an outing around a main occasion plus an added purpose. を兼ねて can present both purposes as substantial and deliberately combined, rather than making the second merely an added use of the occasion. ながら focuses on two actions overlapping in time. かたがた is a formal, courteous pattern associated especially with visits, greetings, thanks, apologies, and reports.
More examples
母は買い物がてら、市役所で住民票を取ってきた。
While out shopping, my mother stopped at city hall to get a copy of her residence record.
Analyze健太はジョギングがてら、河川敷の工事の様子を見てきた。
While out jogging, Kenta went to see how the construction work by the river was progressing.
Analyze私たちは花見がてら、城跡まで足を延ばした。
While out viewing the cherry blossoms, we went a little farther to the castle ruins.
Analyze叔父は墓参りがてら、故郷の友人を訪ねた。
While visiting the family grave, my uncle also visited a friend in his hometown.
Analyze記者は会場を下見がてら、周辺の交通状況も確認した。
While scouting the venue, the reporter also checked traffic conditions in the surrounding area.
Analyze兄は友人を訪ねがてら、近くの美術館にも立ち寄った。
While visiting a friend, my older brother also stopped by a nearby art museum.
Analyze