To reduce an unpleasant feeling given to ambient workers by a plurality of kinds of operating noises generated at random from a plurality of places of a recording medium conveying device during a continuous image forming.

A distance from the pickup roller 21 of a sheet conveying mechanism 4 to a registration roller 27 is set two times as long as a distance from the leading end PS1 of a preceding A4-sized, sideways sheet P to the leading end PS2 of the succeeding sheet P-2, and a pickup electromagnetic clutch 21b and a conveying electromagnetic clutch 24c are simultaneously energized. During the continuous paper feeding, the generation timing of an impact noise when the pickup electromagnetic clutch 21b and the conveying electromagnetic clutch 24c are energized and the generation timing of the impact noise when the sheet P abuts on the registration roller 27 are made coincident with each other.