PURPOSE: To provide an axial-flow blade which increases a ventilating flow rate through automatic fluctuation of the pitch of a blade plate even when it is used for a ventilating fan and used under a high static pressure.

CONSTITUTION: A moving plate 9 is axially movably arranged in a blade boss 6 which has an air hole 5 and on the outer periphery of which blade plates 7 are arranged such that a pitch is variable. Through movement of the moving plate 9, a varying mechanism is arranged such that the pitch of the blade plate 7 is variable and when an axial flow blade is mounted on the rotor shaft 2 of an electric motor 1 for a ventilating fan, the pitch of the blade plate 7 is variable by means of a pressure difference between the indoor side A and the outdoor side B of the moving plate 9.