A limit switch having a housing having a box, an attachment hold made in a side surface of the box, having a cylindrical bearing section, a rotating shaft rotatably inserted through the cylindrical bearing section, a cam unit provided in a leading end portion of the rotating shaft, and an operation lever provided in the other end portion of the rotating shaft. Rotational action of the operation lever is converted into vertical action by the cam unit in the box. A contact of a switch main body accommodated in and fixed to the housing is opened and closed. An outer diameter of the cam unit is smaller than an inner diameter of the attachment hole.