A lock mechanism of the present disclosure includes an engaging member, an operating member, and a drive mechanism. The drive mechanism translates a linear movement of the operating member between a first position and a second position into a rotation of the engaging member between a first rotational position and a second rotational position so that, when the operating member is moved to the first position, the engaging member is rotated to the first rotational position, and, when the operating member is moved to the second position, the engaging member is rotated to the second rotational position. The engaging member includes a pair of engaging pieces around a rotation shaft center, and an engaging-target portion includes a pair of engaging recesses with which the pair of engaging pieces engages when the engaging member lies at the first rotational position, and from which the pair of engaging pieces disengages when the engaging member lies at the second rotational position.