To prevent the deterioration of the peripheral environment by enhancing oil component separation capacity in an oil component separator.

In the oil component separator 11, a cover 15 is fixed to a separator body 12 so as to cover the exhaust port 14 thereof and a sidewall 17 with which exhaust gas collides is formed at the position opposed to the exhaust port 14 of the separator body 12 while a filter 18 and a bypass passage 21 are provided at an upper position not opposed to the exhaust port 14.