To provide a separation device that can reliably feed sheet members in a simple configuration so as to prevent feeding failure caused by sticking of the sheet members such as a recording sheet, and to provide a paper feeding cassette using the same, and an image forming apparatus.

The separation device 82 for separating the sheet members 6 disposed in the uppermost position where the sheet members 6 are stored includes a cylindrical rotation member 821 composed of an soft elastic body. The device makes the rotation member 821 contact with a side face of the sheet members 6 from a feeding perpendicular direction and rotate separates the sheet members 6.