PURPOSE: To provide an insert loader device capable of easily adjusting insert loader pressing in head (inserting head) in conformance with cases that a sleeve fitting is different depending on a model of cylinder block or a diameter of sleeve fitting is different.

CONSTITUTION: Pitch positioning members 15, 16 are selected from plural corresponding to the interval of a sleeve fitting 2 to be assembled into a cylinder block 1, these are fixed on a supporting member 6, enabling to set the interval of the sleeve hardware 2 optimum. In addition, an inserting head 10 is selected from plural corresponding to the diameter of the sleeve hardware 2 to be assembled into the cylinder block 1, the sleeve fitting 2 of many diameters is fixed to the inserting head 10 by fixing the inserting head to a shaft body 9.