An image forming apparatus and an image forming method, which are capable of forming images at stable image quality by executing adjustment of operating conditions at appropriate timings, are provided. When a Vsync count corresponding to an integrated value of a rotation count of an intermediate transfer belt reaches a predetermined value V1 or V2, a charging current Iw is increased by one level and an adjusting operation of a developing bias is executed (at a time t4 or t5), to thereby stabilize an image density. Further, when remaining service life of a developer reaches a predetermined value (50%) (at a time t6), if the Vsync count at that moment suggests that the time to change the charging current Iw is drawing near, the change thereof is executed ahead of the schedule, whereby the adjusting operation of the developing bias, which should otherwise be executed at the time t7, is omitted.