A method for manufacturing a spring member of a sealing device, the method being characterized by comprising: an inner circle and outer periphery punching step that includes an inner circle punching step and an outer periphery punching step, the inner circle punching step punching a circle portion out of a plate material (a) made of a metal material to form an inner circle end portion having an inner circle defining a circle space, the outer periphery punching step punching, out of the plate material (a), a portion outside of an outer circle that is a circle outside of the inner circle end portion, and outer periphery radial portions that are portions radially extending outside of the inner circle end portion up to the outer circle, to form a plurality of radial pieces aligned radially; an inner periphery bending step that, in the plate material (b) having undergone the inner circle and outer periphery punching step, bends a portion inside of a base circle that is a circle between the inner circle end portion and the outer circle, from the base circle toward one side that the plate material (a) faces; an inner periphery punching step that, in the plate material (c) having undergone the inner periphery bending step, punches out inner periphery radial portions that are portions radially extending from the inner circle end portion to inside of the outer circle, to divide the inner circle end portion and form a slit in each of the radial pieces, the slit extending inside of the outer circle; and an outer periphery bending step that, in the plate material (d) having undergone the inner periphery punching step, bends a portion outside of the base circle from the base circle toward the one side. an inner circle and outer periphery punching step that includes an inner circle punching step and an outer periphery punching step, the inner circle punching step punching a circle portion out of a plate material (a) made of a metal material to form an inner circle end portion having an inner circle defining a circle space, the outer periphery punching step punching, out of the plate material (a), a portion outside of an outer circle that is a circle outside of the inner circle end portion, and outer periphery radial portions that are portions radially extending outside of the inner circle end portion up to the outer circle, to form a plurality of radial pieces aligned radially; an inner periphery bending step that, in the plate material (b) having undergone the inner circle and outer periphery punching step, bends a portion inside of a base circle that is a circle between the inner circle end portion and the outer circle, from the base circle toward one side that the plate material (a) faces; an inner periphery punching step that, in the plate material (c) having undergone the inner periphery bending step, punches out inner periphery radial portions that are portions radially extending from the inner circle end portion to inside of the outer circle, to divide the inner circle end portion and form a slit in each of the radial pieces, the slit extending inside of the outer circle; and an outer periphery bending step that, in the plate material (d) having undergone the inner periphery punching step, bends a portion outside of the base circle from the base circle toward the one side.