To provide a door opening/closing device facilitating installation work for opening/closing and locking an opening with nothing to obstruct passing.

A door rail 101 is fitted to the upper end of a sliding door body 2. A frame rail 51 is slidably fitted to the door rail 101 along the longitudinal direction. The frame rail 51 is fitted to one side of the upper end of an opening frame. The sliding door body 2 is moved to close the opening frame. A locking grip 124 of the sliding door body 2 is moved upward to project a latch 167 toward the upper part of the sliding door body 2. The movement of the sliding door body 2 in the opening direction in relation to the opening frame is regulated by the projection of the latch 167. The sliding door body 2 closing the opening frame can be locked without machining both inner side faces of the opening frame. There is nothing to get in the way when passing the opening frame opened by the sliding door body 2. Work execution for opening/closing and locking the opening frame is facilitated.