PURPOSE: To improve operation reliability by forming a centrifugal weight having a substantially U-shaped cross section and by moving and guiding the centrifugal weight on a guiding surface provided on a leg part, in a device which rotates a pair of eccentric bodies by centrifugal force occurring at the centrifugal weight to rotate a cam shaft of an injection pump.

CONSTITUTION: In the device, an adjusting disk 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 18 formed in the driving member 1 accommodates a bearing flange 3 integral with a cam shaft 2 of an injection pump, an adjusting device hub 5 connected with the cam shaft 2 is combined with the driving member 1 through a pair of eccentric rings 20 which are journalled in the adjusting disk 14 and is rotated by a centrifugal weight 25. In this case, the centrifugal weight 25 is formed so as to have a substantially U-shaped cross section by projecting two leg parts 31 from a weight body 30, and a guiding surface 34 is provided for a wall part 33 projecting from each leg part 31. A bracket 36 is projected on the guiding surface 34, and a return spring 26 is placed between the brackets 36, 36 of facing centrifugal weight 25.