A refrigerant compressor is provided that can be assembled easily and can quickly discharge lubricating oil that leaks from contact sliding parts of its mechanical seal so as to prevent the oil from turning into sludge around the stationary ring. In a refrigerant compressor in which a mechanical seal which shaft seals the inner side and the outer side of a housing is installed at a portion of the housing through which a rotating shaft penetrates, a mechanical seal comprises a stationary ring securely fastened to the inner circumferential surface of a boss portion, a rotary ring securely fastened to the outer circumferential surface of the rotating shaft to the inside of the stationary ring so as to face the stationary ring, whereby sliding contact is formed between sides of the stationary ring and the rotary ring. The inner circumferential surface of the boss portion to the outside of the stationary ring is provided with an inclined portion over the entire circumference or at least the gravitationally lower portion of the inner circumferential surface, which enlarges from the stationary ring side toward an oil discharge hole to the outside of the stationary ring.