In a rotary type image developing apparatus that has a rotary rack accommodating a plurality of developer units and drives the rotary rack to rotate in a predetermined rotational direction so as to bring a targeted one of the developer units to a developing position, each developer unit includes a toner storage in which a first slope is disposed. As the rotary rack rotates, toner that remains upstream of a toner supply opening in a toner flowing direction in the toner storage is guided by a slope surface of the first slope, which enables the toner to be smoothly supplied to a developing chamber. Thus, even when the toner gets low, the toner can be efficiently supplied from the toner storage to the developing chamber with the aid of the first slope.