Abstract: A rotor-fixing resin composition of the present invention comprising: an epoxy resin-containing thermosetting resin; a curing agent; and an inorganic filler, wherein a tensile elongation at break-a is 0.1% or higher and 1.7% or lower, the tensile elongation at break-a is obtained by subjecting a test piece to a tensile test pursuant to JIS K7162 under conditions of a temperature of 120° C., a test force of 20 MPa and 100 hours, and the test piece is a cured product produced by subjecting the rotor-fixing resin composition to curing by heating at 175° C. for 4 hours, and molding to a dumbbell shape pursuant to JIS K7162.