A scroll compressor includes a fixed scroll and an orbiting scroll, each including a spiral wrap protruding from an end plate and having the same tooth thickness (Tr) and the same base-circle radius (b) defining an involute surface. The fixed scroll and the orbiting scroll are offset from each other by an orbiting radius (ρ) and mesh such that the respective wraps face each other with a phase shift of 180°. The orbiting scroll revolves/orbits along a circular orbit with the orbiting radius (ρ) to compress a gas while a rotation-preventing mechanism prevents rotation of the orbiting scroll. The relationship between the involute surfaces of the spiral wraps of the two scrolls and the dimensions, dimensional tolerance, and assembly standards of the rotation-preventing mechanism are determined so that the median value of an allowable angle of rotation (φ) agrees with an upright position of the orbiting scroll.