Provided is a structure with which it is possible to inhibit rubbing of an electric contract surface during insertion of a developer cartridge. This developer cartridge 1 has a casing capable of containing a developer, a development roller 30, a memory medium 51 having an electric contact surface, a holder 52 capable of moving with the electric contact surface, and a pressing member 53. The holder 52 is capable of moving in a first direction relative to the casing. When the holder 52 is moving, the pressing member 53 presses the holder 52 while moving in a second direction. During insertion of the developer cartridge, the holder 52 and the electric contact surface move in the first direction in relation to the casing. It is thereby possible to inhibit rubbing of the electric contact surface.