Punching device, sheet processor having the punching device, and image forming apparatus having the punching device

There is provided a punching device including: a die member having a plurality of die holes formed therein; a plurality of punch members which are caused to advance into the die holes to punch holes in a member to be punched; an operating member having cam portions formed along a direction intersecting the direction of advancement of the punch members, the operating member being moved along the direction intersecting the direction of advancement of the punch members to cause by a conversion function of the cam portions the punch members to advance into the die holes; and a drive unit for selectively causing advancement of the plurality of punch members by changing the direction of movement of the operating member. In the punching device, each of the cam portions has a straight groove and a cam groove for performing the conversion function, and when the operating member is moved in one of opposite directions, at least one of the cam grooves of the cam portions acts on one of the punch members to selectively cause the same to advance.