To compose a third connection part so as to have sufficient strength against a work load imposed on the third connection part by increasing the shaft diameter of the third connection part in a pump shaft without causing such inconvenience that a hydrostatic continuously variable transmission has large capacity, and becomes large and expensive.

In the pump shaft 24 of the hydrostatic continuously variable transmission 3 having power from an engine 1 transmitted, a second connection part 37 for connecting a cylinder block 32 in an integrally rotating form, a second bearing part 39 supported to a port block 17 through a second bearing 38, and a third connection part 40 connected to a power transmission system on the sides of power extraction shafts 26 and 27 are respectively formed in different-diameter fitting parts having the same size and the same shape, and the bearing part 39 is fitted into the second bearing 38 by interlaying a collar 43 fitted onto the bearing part 39 in an integrally rotating form.