A scroll type fluid apparatus having a rotation preventing mechanism provided with a sliding member engageable with the outer surface of a bearing portion at an orbiting scroll and regulating the radial movement of the sliding member in reciprocating movement, and a sliding member holder engageable with the outer surface of the sliding member so as to regulate the movement of the sliding member in the direction perpendicular to the moving direction of the bearing portion. Spaces formed before and behind the sliding member in the sliding direction thereof are utilized as oil chambers respectively, whereby lubricating oil pumped-up from an oil pickup provided at a crankshaft is forcibly fed by the pump action caused by sliding motion of the sliding member onto the slidable contact surface of a thrust bearing supporting the orbiting scroll.