Abstract: The purpose of the present invention is to provide a vane pump that is able to prevent decrease of power transmission efficiency when the vane pump is used in combination with a device such as a transmission device, for example. Therefore, this vane pump (10, 20, 50, 60, 70, 80, 90) has a hollow shaft (1, 21, 51, 61, 71, 81, 91), the hollow shaft (1, 21, 51, 61, 71, 81, 91) is configured such that a hollow portion thereof allows a rotation driving shaft (which is, for example, an input shaft 103 of a transmission device as illustrated in FIG. 1, and, which also includes an input shaft which is inserted directly into the transmission device from a driving source 102 without having a coupling interposed therebetween) of the driving source (102) to be inserted therethrough, and the hollow shaft (1, 21, 51, 61, 71, 81, 91) and the rotation driving shaft (103) are coupled by means of a mechanism (spline, key and key groove, etc.) for transmitting a torque but transmitting no thrust.