To solve the problems of the amplification of vibration between driving motors or an increase in unwanted driving noise, even in a driving unit device using multiple driving motors.

A driving unit device 40 according to the present invention includes a driving holder body 41 and a cover body 42 which hold therebetween gear trains 45, 46 relaying power transmission from driving motors 43, 44 to photoreceptor drums 3 etc. and pivotally support them at both end sides in the respective axial directions thereof, and further includes at least two driving motors 43, 44. A first wall part 51, which connects and supports the driving holder body 41 and the cover body 42, is disposed so as to make a vertical width direction V thereof cross the direction of aligning motor axes 43a, 44a in a group of the driving motors 43, 44. A second and a third wall part 52, 53, which connect and support the driving holder body 41 and the cover body 42, are disposed so as to extend in a horizontal width direction H orthogonal to the vertical width direction V of the first wall part 51 and hold the first wall part 51 therebetween at both sides in the vertical width direction V of the first wall part 51.