The present invention provides a housing structure of a door mirror in which a fixed-side housing portion is reliably crimped to a fixing-side housing portion on the surface side of a housing. In the housing structure of a door mirror, a boss portion and a contact piece are located on the deeper side than first and second butting portions located on the surface side, and a projection portion is located farther than a screwing portion in a positional relationship in the vertical direction (an arrow Y direction) with respect to a horizontal plane passing through the first butting portion. Therefore, when the boss portion (first mounting portion) of an upper housing (fixing-side housing portion) and the contact piece (second mounting portion) of a lamp assy (fixed-side housing portion) are fixed by a screw, a screw tightening force can be concentrated on the projection portion as shown by an arrow A, and this force can be made to act on the first and second butting portions as shown by an arrow B.