A method for producing a progressive-addition plastic lens having a prism thinning applied thereto without cutting and polishing includes: a lens molding die forming step of forming a lens molding die configured by a first molding die having a molding face for forming one optical surface, which is a progressive-addition surface, of the lens and a second molding die having a molding face for forming the other optical surface of the lens, wherein the first molding die and the second molding die are arranged so that the respective molding faces thereof face inner side; a filling step of filling a lens material liquid containing a monomer composition into the formed lens molding die; and a curing step of polymerizing and curing the filled lens material liquid so as to form the lens. The molding face of the first molding die is formed so that a normal line at a point where the molding face of the first molding die intersects with a reference axis of the first molding die is inclined in the vertical direction with respect to the reference axis of the first molding die.