A power unit support structure to minimize vibration of a vehicle body frame. A mount bracket disposed on a vehicle body frame supports a power unit that includes a longitudinal engine. Specifically, the mount bracket is disposed substantially at a center in a vehicle width direction between a pair of right and left center side frames that form part of the vehicle body frame and extend in a vehicle fore-aft direction. The center side frames are connected together with cross members. The mount bracket is mounted to the cross members via a connection member as a vibration damping material. The power unit is then mounted to the mount bracket via a subframe.