COLOR IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To provide a color image forming apparatus capable of simultaneously detecting displacements of a toner image, formed by imaging units for every color, in both of a main scanning direction and a sub scanning direction and capable of detecting the displacements in both the directions in a short time.SOLUTION: A resist pattern comprises a reference color line consisting of at least one line, and an detection object color pattern consisting of a plurality of lines, and the respective lines are formed at different positions in the sub scanning direction and extend in the main scanning direction. The plurality of lines constituting the detection object color pattern extend in the main scanning direction with one virtual straight line running in the sub scanning direction defined as a reference position, and the length dimension of the respective lines in the main scanning direction are formed stepwise long or short at uniform length dimensions. The displacements of the toner image in the main scanning direction and the sub scanning direction are simultaneously detected based on the detection result, by a sensor, of the resist pattern formed by the respective imaging units.