PURPOSE: To make it possible to carry out the adjustment of a relative angle between both scroll members, externally of a housing, by forming a hole having a depth in a stationary scroll member and as well forming a hole piercing through a front end plate at a position opposing the above-mentioned hole.

CONSTITUTION: After a movable scroll member 26, a movable scroll member drive mechanism, a rotation inhibiting mechanism 37 are disposed in a cup- shaped casing 12 securing a stationary scroll member 25, a front end plate 111 is arranged to close the opening of the cup-shaped casing 12. Thereafter, an angle adjusting rod 40 as shown in the drawing, is inserted into an angle reference hole 113 from the outside of the front end plate 111 so that the front end of the angle adjusting rod 40 is sufficiently inserted in an angle setting hole 225 in the stationary scroll member 25. In this condition the front end plate 111 is fastened to the cup-shaped casing 12 with bolts and nuts, thereby a relative angle between both scroll members may be adjusted.