To provide a driving device for a vehicular power seat device capable of reducing the number of components for holding connection parts.

The driving device 1 for a vehicular power seat device comprises an electric motor 2, a speed-reduction gear mechanism 3, and a gear housing 4. The gear housing 4 is composed of a housing body 41 having a concave space 411 for housing the speed-reduction gear mechanism 3, a cover 42 fixed to the housing body 41 for covering the concave space 411, and a locking member 43 formed on the housing body 41 for locking the cover 42 on the housing body 41 by rotating the cover 42 relative to the housing body 41. The device comprises a fixing part 53 formed on a bracket 5 for fixing the gear housing 4 and a regulation part 54 formed near the fixing part 53 of the bracket 5 for regulating the rotation of the cover 42 relative to the housing body 41 in a state that the gear housing 4 is fixed to the bracket 5.