A developer supply apparatus includes a portion receiving a developer supply container and being movable between mounting/demounting and developer supply positions, a mechanism for moving the container receiving portion between its two positions by a manually operable lever, and a mounting discrimination member on the container receiving portion movable therewith and operatively connected with the lever and provided for relative movement between the mounting discrimination member and a portion to be discriminated provided on the developer supply container in interrelation with a moving operation of the lever. When the mounting discrimination member makes relative movement to reach a regular position, the container receiving portion moves to the developer supply position, and when the mounting discrimination member makes relative movement, and the discrimination member interferes with the portion to be discriminated before reaching the regular position, the container receiving portion is prevented from moving to the developer supply position.