A polyester resin for compression molding comprising chiefly ethylene terephthalate units and having an inherent viscosity in a range of 0.6 to 1.3 dL/g, containing a diethylene glycol in an amount of smaller than 2.3 mol %, and containing a monohydroxyethyl terephthalate and a bishydroxyethyl terephthalate in a total amount of not larger than 0.005% by weight. A mass of a molten resin which is the polyester resin can be fed to a compression-molding apparatus maintaining stability for extended periods of time, featuring excellent properties for being conveyed and for enhancing the productivity.