A lock structure includes: an engaged body; and an engaging body capable of inserting and removing the engaged body along insertion and removal directions opposite to each other. An engaged body includes first and second engaged walls disposed opposite to each other at an interval, a connection wall which connects end portions on the insertion direction side thereof, and an engaged protrusion protruding from an outer wall surface of the second engaged wall. An engaging body has first and second engaging walls in which a space between the respective inner wall surfaces is defined as an accommodation space of the engaged body, an engaging protrusion protruding from the inner wall surface of the second engaging wall and capable of locking the engaged protrusion on the removal direction side, and a third engaging wall disposed between the first and second engaging walls.