In a developing device included in an electrophotographic image forming apparatus, a device for replenishing toner to the developing device has a toner container having a hollow cylindrical body. The body is formed with a toner outlet at the center of one end thereof. A holder arrangement holds the container such that the toner can be delivered to a toner inlet portion included in the developing device. A drive mechanism causes the container to rotate about its own axis. The holder arrangement is formed with an opening for feeding the toner flowing out via the toner outlet to the toner inlet portion. The opening is covered with an elastic member having a holed portion. The device is capable of replenishing a predetermined amount of toner to the developing device at all times.