A development device that has communication port sealing means for sealing a communication port communicating a developer supporter container with a developer container. The development device is advantageous in cost reduction, easy manufacturing, and formation of high-quality images. In the development device which has a developing roller container for containing a developing roller, a developer container for containing a developer, a base member for forming a communication port communicating the developer roller container with the developer container, and a seal member that is adhered to the base member so as to cover the communication port, and which cancels sealing of the communication port by peeling off the seal member from the base member by pulling out the seal member in a direction parallel to an opened surface of the communication port, the base member is composed of a polypropylene resin having a bent section, and the seal member is adhered to the base member by thermal compression bonding.