Abstract: The mold comprises a stationary mold half (31) and a movable mold half (32). An annular groove (33) surrounding a cavity (30a) formed by the stationary mold half (31) and the movable mold half (32) is formed in one of the stationary mold half (31) and the movable mold half (32), and a mold seal member (36) formed of a silicon rubber is disposed in the annular groove (33). A mold seal groove (37) opposed to the mold seal member (36) is formed in the other of the stationary mold half (31) and the movable mold half (32). The mold seal member (36) is projected from the contact surface of the stationary mold half (31) or the movable mold half (32) and comprises a fitting part (36a) fittedly installable in the mold seal groove (37). The cross sections of the fitting part (36a) and the mold seal groove (37) are formed in an approximately same shape.