PURPOSE: To improve operation reliability by guiding a flyweight with a support member rotatably supported in an adjusting device, in a device which rotates a pair of eccentric bodies by centrifugal force occurring at the flyweight to rotate a cam shaft of an injection pump.

CONSTITUTION: In this device, an adjusting device plate 14 having a cylindrical additional part 13 is engaged into a turning part 9 of a gear-shaped driving member 1, and is fixed with screws 16. An annular space made of a cutout 18 formed in the driving member 1 accommodates a support flange 3 integral with a cam shaft 2 of an injection pump in it, an adjusting device hub 5 connected with the cam shaft 2 is combined with the driving member 1 through two pairs of eccentric bodies 20 which are journalled in the adjusting device plate 14 and are rotated by a flyweight 25. In this case, the flyweight 25 is provided so that it is radially guided by a support member 27 with centrifugal force against a return spring 26, and this movement rotates the eccentric body 21 via a journalling pin 28.