A mirror surface angle adjusting device includes: a pivot plate (10) which supports a mirror (6) and is attached to a holder (9) pivotably three-dimensionally on a pivot shaft (76); a bracket (8) disposed on a vehicle body; a mirror tilting drive section (11) contained between the bracket (8) and the holder (9) attached to the bracket (8); an operation shaft (44A, 44B) of the mirror tilting drive section (11), the operation shaft penetrating through the holder (9) and being connected to the pivot plate (10); a detection rod (101A, 101B) which moves following the pivot plate (10); an angle detection section (100) which detects a tilt angle of the pivot plate (10); a pivot depressed portion (80) into which the pivot shaft can be press-fitted; and a gear positioning rib (69) provided on an inner wall of the holder (9) to position the mirror tilting drive section (42).