Provided is an image forming apparatus that suppresses degradation of performance of processing up to completion of printing while suppressing the occurrence of moire. A data-compression unit stores identification data indicating the presence or absence of periodicity obtained by analyzing printing data, and printing data correlated with the identification data in a first memory area of a RAM. A color-conversion-processing unit that performs a speculative process, causes printing data that has undergone a color conversion process corresponding to printer printing to be stored in a second memory area of a RAM. A screen-processing unit that performs a speculative process, performs an AM screen process on printing data. In addition, a system-control unit causes the image-forming unit to move from a printing pre-start position to a printing start position based on a determination result of a printing color in a color conversion process corresponding to a first printer printing by the color-conversion-processing unit by a speculative process.