expression
sic; as in the original text
Used in quotations to indicate that the text is reproduced exactly as it appears, including any errors or unusual phrasing. Equivalent to Latin 'sic'.
See also: 原文のまま
彼のメールには「明日、会議があります（原文ママ）」と書いてあった。
His email said, 'There is a meeting tomorrow (sic).'
新聞記事の引用部分に（原文ママ）と注釈が付いていた。
The quoted part of the newspaper article had a note saying (as in the original).
A longer phrase meaning 'as it is in the original text', used in ordinary sentences rather than as a parenthetical note. 原文ママ is a fixed expression specifically used as a notation.
From 原文 (original text) + まま (as it is). The katakana ママ is often used for emphasis or clarity in this fixed expression.