To obtain a chopped strand mat enabling use of a liquid unsaturated polyester resin wherein the concentration of a styrene is lower than usual, at molding FRP by a hand lay-up method, so as to protect a working environment.

A powdery unsaturated polyester prepared by using as a material a glycol or the like obtained by adding a propylene oxide to OH groups in both ends thereof is made chopped strands. In a state wherein the chopped strands are stuck by a sticking amount of 1-10 wt.% to the weight of the chopped strand mat to be obtained, the unsaturated polyester is heated to the softening point or above and then cooled and pressed, and thus the chopped strands are molded in the shape of the mat having a thickness of 2 mm or below, with the unsaturated polyester used a binder.