A sheet cutter includes: a stationary knife including a straight blade part formed in a straight-line shape in a longitudinal direction; a movable knife including a cutting edge part formed in the shape of V-character, opposed to mesh with the straight blade part of the stationary knife, the movable knife being able to freely move toward or back from the stationary knife; a movable knife pressing member for pressing the movable knife against the stationary knife; and a movable knife driver driving the movable knife forward or backward. The movable knife pressing member pressure contacts the movable knife against the stationary knife by a compression coil spring contained inside the movable knife pressing member.