An upper module (1) has a cavity member (6) constituting the inner bottom face (5) of a cavity (4) and a surround member (7). The cavity member (6) is a low-adhesion material according to the present invention which is composed of a body (8) and a face (10) formed on the underside (9) of the body (8) that is to come into contact with a fluid resin. The body (8) is made of a material consisting of the first material 3YSZ and the second material ZrN at a prescribed ratio. The face (10) is made of Y2O3 exhibiting low adhesion to cured resins and has a lower thermal expansion coefficient than that of the body (8). The cavity member (6) is produced by joining the body (8) and the face (10) at high temperature and then cooling the obtained composite, whereby a compressive residual stress is generated in the face (10) owing to the difference in thermal expansion coefficient and remains in the face (10).