A filter for an oil catch apparatus is provided. The oil catch apparatus is capable of efficiently extracting oil from air flowing through the oil catch apparatus while being of compact size. The filter includes a cylindrically wound main filter unit, a first keep member for keeping one end of the main filter unit, and a second keep member for keeping the other end of the main filter unit. Air flowing into the main filter unit from an opening formed in the first keep member is cleared of impurities upon passing through the main filter unit, and exits out of the main filter unit.