An attachment structure for attaching a recess of a housing to a DIN rail includes first and second movable strips. The first movable strip extends continuously from an operable portion and being movable along a surface of the housing in a first direction toward the recess and in a second direction opposite from the first direction. A first claw of the first movable strip and a second claw of the second movable strip move toward the DIN rail in accordance with a movement of the first movable strip in the first direction and engage ledges of the DIN rail. A koma converts the movement of the first movable strip in the first or second direction to a movement of the second movable strip in a direction opposite from the movement direction of the first movable strip.