To provide a tandem pump unit allowing the improvement of the efficiency for the work of mounting it in a vehicle.

First and second hydraulic pimp 10a, 10b have respective first and second pump shafts 11a, 11b arranged in parallel relationship with each other within a housing 20 and operatively connected to each other by a power transmission mechanism 40, respective first and second movable swash plates 14a, 14b for varying the amounts of oil delivered/sucked, and respective first and second control shafts 15a, 15b for tilting the first and second movable swash plates. The first and second control shafts 15a, 15b are arranged to extend in a direction in which they are separated from each other along the cross direction of the vehicle.