Patent ID: 8670014

Claim:
An image forming apparatus comprising: an image forming unit that includes a rotation member which is used for image formation, and on which a mark indicating a reference position for image formation is formed; a detection unit configured to detect the mark on the rotation member and output one or more reference signals; a control unit that causes the image forming unit to start a preparation processing, and then causes the image forming unit to start an image forming processing for the image of a first color in response to outputting a completion signal indicating that the preparation processing is completed; and a timing unit configured to measure, when outputting the completion signal, a time period from when the detection unit has output a first reference signal immediately before outputting the completion signal until the completion signal is outputted, wherein the control unit considers the time period measured by the timing unit as a waiting period, and causes the image forming unit to start the image forming processing for the image of subsequent colors following the first color when the waiting period has elapsed after outputting a second reference signal following the first reference signal.