To enlarge a blade for a wind power generation apparatus by reducing lightning damage to the blade for the wind power generation apparatus and suppressing torsional deformation of the blade.

In a blade 1 for a wind power generation apparatus, a main beam 4 is comprised of a PAN-based carbon fiber composite resin molded body, and an outer skin part 3 is comprised of a carbon fiber composite resin molded body in which pitch-based carbon fibers are disposed in a double bias shape. The main beam includes a web part and a beam overlapped to the outer skin part, and a ratio t1/t2 of thickness (t1) of the pitch-based carbon fiber composite resin molded body of the outer skin part and thickness (t2) of the PAN-based carbon fiber composite resin molded body of the beam is 0.01 to 0.1.