PURPOSE: To provide the damper pulley device of a mechanical supercharger, wherein torque fluctuation of an output shaft of an engine can be absorbed by its structure simplified without necessitating any special stopper, and increase of the number of parts and costs can be avoided.

CONSTITUTION: A plurality of receiving side recessed grooves 23 each of which the section is formed into an arc shape having the desired radius of curvature, and extended in the axial direction of an input shaft 13 are formed on the outer peripheral surface of a boss part 21 of a damper pulley 19 to be fixed to the input shaft 13 end, and a plurality of pressing recessed grooves 24 each of which the section is formed into an arc shape having the desired radius of curvature, and extended in the axial direction of the input shaft 13 are so formed as to face respective receiving side recessed grooves 23. And rod-like elastic members 25 such as rubber, having the radius smaller than the radius of curvatures of both recessed grooves 23, 24, and for supporting the pulley main body 22 concentric with the boss part 21 are interposed between the receiving side recessed grooves 23 and the pressing side recessed grooves 24 faced to each other.