An image pickup apparatus comprising: a mirror unit configured to enter a shooting optical path at a time of observation through a viewfinder, and retract from the shooting optical path at a time of shooting; a positioning member (404, 504) with which said mirror unit having entered the shooting optical path is configured to come into contact so as to be positioned in the shooting optical path; a bounce suppressing member (401, 501) comprising a lock pin (402, 502) configured to suppress bounce of said mirror unit that has come into contact with said positioning member (404, 504); and an adjustment member (403, 503) comprising a first shaft portion (403a, 503a) to which said positioning member (404, 504) is fixed and a second shaft portion (403b, 503b) on which said bounce suppressing member (401, 501) is rotatably fitted, the second shaft portion (403b, 503b) being coaxially provided with the first shaft portion (403a, 503a), and the first shaft portion (403a, 503a) and the second shaft portion (403b, 503b) being eccentric from a rotational center of said adjustment member (403, 503), wherein when said mirror unit is inserted into the shooting optical path and is in contact with said positioning member (404, 504), said mirror unit is configured to move following the movement of said positioning member (404, 405), and wherein, when said adjustment member (403, 503) is rotated, said bounce suppressing member (401, 501) and said positioning member (404, 504) are configured to eccentrically move according to the rotation of said adjustment member (403, 503), and said positioning member (404, 504) and said bounce suppressing member (401, 501) is configured to move in substantially the same direction at over substantially the same travel distance, and a gap between said mirror unit and the lock pin (402, 502) in said bounce suppressing member (401, 501) before and after the rotation of said adjustment member (403, 503) and the movement of said mirror unit is substantially constant. a mirror unit configured to enter a shooting optical path at a time of observation through a viewfinder, and retract from the shooting optical path at a time of shooting; a positioning member (404, 504) with which said mirror unit having entered the shooting optical path is configured to come into contact so as to be positioned in the shooting optical path; a bounce suppressing member (401, 501) comprising a lock pin (402, 502) configured to suppress bounce of said mirror unit that has come into contact with said positioning member (404, 504); and an adjustment member (403, 503) comprising a first shaft portion (403a, 503a) to which said positioning member (404, 504) is fixed and a second shaft portion (403b, 503b) on which said bounce suppressing member (401, 501) is rotatably fitted, the second shaft portion (403b, 503b) being coaxially provided with the first shaft portion (403a, 503a), and the first shaft portion (403a, 503a) and the second shaft portion (403b, 503b) being eccentric from a rotational center of said adjustment member (403, 503), wherein when said mirror unit is inserted into the shooting optical path and is in contact with said positioning member (404, 504), said mirror unit is configured to move following the movement of said positioning member (404, 405), and wherein, when said adjustment member (403, 503) is rotated, said bounce suppressing member (401, 501) and said positioning member (404, 504) are configured to eccentrically move according to the rotation of said adjustment member (403, 503), and said positioning member (404, 504) and said bounce suppressing member (401, 501) is configured to move in substantially the same direction at over substantially the same travel distance, and a gap between said mirror unit and the lock pin (402, 502) in said bounce suppressing member (401, 501) before and after the rotation of said adjustment member (403, 503) and the movement of said mirror unit is substantially constant.