To provide a door opening/closing device capable of reliably closing even a heavy door with a simple structure.

In this door opening/closing device, a guide rail 7 is fixed at a required interval to the upper end of a wall surface and the other door fixing surface, a rolling roller is loosely inserted into a fixing shaft on the upper end of a door plate 1, a spring for pressing the door plate 1 to the fixing surface side toward a guide rail 7 surface is made to act on a rolling roller shaft, an inclined face for guiding the door plate 1 in the lowering direction at closing time and guiding the door plate 1 in the raising direction at opening time is formed on the upper end of the guide rail 7, and a fastener for reliably sealing a door by a movement of the door plate 1 is arranged.