PURPOSE: To enable each connecting member to be made large in diameter, and thereby enhance mechanical strength and twisting strength by forming each space to which connecting members can be inserted, in a housing at each place corresponding to the connecting members of both drive shafts in plural gear pumps.

CONSTITUTION: In the multiple connected gear pump device, a first and a second pump 3 and 5 are disposed in series in the inside of a housing 1. And the first and second pumps 3 and 5 allow the respective gears 27 and 43 of respective shafts 29 and 45 to be meshed with the drive gears 25 and 41 of respective drive shafts 19 and 35. The respective drive shafts 19 and 35 are connected to each other with a coupling 103. By this constitution, a space 101 sufficiently large enough for the coupling 103 to be inserted, is formed in the radial direction at a place corresponding to the coupling 103 in the housing 1. One end of the space 101 is opened at a shaft hole 53 formed in the body 15 of the housing 1, and the other end of the space is concurrently opened to the outside of the housing 1.