To provide a tandem pump unit allowing simplification of the operation of mounting it in a vehicle and a reduction in cost through a reduction in number of part items.

The tandem pump unit includes a common housing 20 accommodating first and second hydraulic pumps 10a, 10b, and first and second center sections 30a, 30b supporting the respective hydraulic pumps, the common housing having first and second openings 20a, 20b formed at both axial ends of a pump shaft for enabling the first and second hydraulic pumps to be inserted therein, and a bearing wall 20c formed in a portion intermediate between the first and second openings. The first and second center sections are connected to the common housing in such a way as to close the first and second openings while supporting the first and second pumps. The connections of the pump shafts of the first and second hydraulic pumps are supported by the bearing wall of the common housing.