To provide a member fixing structure capable of fixing a fixed member to a shaft without rattle so that looseness of a screw hardly occurs.

A recessed groove 4 is provided as a rotational direction regulating portion at a shaft end of the shaft 1, and a protruding ridge 5 is provided at an inner wall of a sleeve portion with a bottom 2a of the fixed member 2 as the rotational direction regulating portion. A taper surface 6 is formed at the protruding row 5 of the fixed member 2, and the side surface of the protruding ridge 5 is made narrower toward the bottom wall. The shaft 1 is inserted into the sleeve portion with bottom 2a of the fixed member 2, the recessed groove 4 and the protruding ridge 5 are engaged, and the shaft 1 is inserted to screw the screw 3 into screw holes 3a, 1a. As the width of the protruding ridge 5 becomes narrower, the recessed groove 4 of the shaft 1 and the protruding ridge 5 of the fixed member 2 are engaged firmly, and the taper surface 6 of the fixed member 2 bites in the side surface of the recessed groove 4. The shaft 1 is fixed at the fixed member 2 firmly, thus the rattle in a rotational direction is almost eliminated and looseness of the screw 3 is prevented.