This disclosure discloses a DIN-rail mount type device. The DIN-rail mount type device includes a housing, a rail groove provided along a width direction of the housing on a face of the housing and being capable of fitting with the DIN rail, a slider groove provided along a width direction of the rail groove on the face of the housing; and a lock member. The lock member configured to slide so as to move forward and backward with respect to the rail groove in the slider groove, and to be able to retain a fitting state between the rail groove and the DIN rail by engaging a one-side end with an engagement portion of the DIN rail fitted into the rail groove.