PURPOSE: To prevent constraint at the end part of a tip seal groove and attain improved efficiency and reliability and preferable, low-cost mass production, by forming a tip seal groove having a given inner part and a central part on the end surface of a scroll wrap body.

CONSTITUTION: A first scroll member 76 is provided with a first involute scroll wrap body 80 erecting integrally with a driving scroll end plate 82. A second scroll member 78 is provided with a second idler scroll wrap body 100 disposed in contact with a driven scroll wrap 80. The driven scroll wrap 80 and the idler scroll wrap 100 are formed with tip seal grooves 140 respectively. The respective tip seal grooves 140 are formed with inner parts 152 protruding from the inner ends of the grooves along the inner wall by a specified length of L. The center part having comparatively narrow width is formed, which is widened from the inner part to the outer end.