A compressed air filter apparatus includes a main flow path as a flow path in which compressed air should circulate, formed in a body to extend from a first opening into a penetration hole, an upper inner flow path extending from the penetration hole to an upper inner space, an upper inner and outer flow path extending from the upper inner space to an upper outer space to pass through an upper filer element, a communication flow path extending from the upper outer space to a lower outer space to pass through a communication hole, a secondary flow path extending from the lower outer space to a second opening, a lower inner flow path extending from the penetration hole to a lower inner space, and a lower inner and outer flow path extending from the lower inner space to the lower outer space to pass through a lower filter element.