PURPOSE: To improve the damping effect of pressure variation component through expansion or resonance muffler effect while to improve the efficiency of compressor by forming a recess in a partition board placed between a bearing and a delivery cover while forming a hole through the inside face of said recess.

CONSTITUTION: A recess 14 for containing a valve 14 is made in the counter cylinder face 13a of bearing 13 for supporting a crank shaft. A partition board 15 is placed between the bearing 13 and a delivery cover 16 to form a valve chamber 14c with said recess 14. Here, an approximately C-shaped recess 15a partially corresponding with said recess 14 while concave to the opposite side from said recess 14 is formed around the bearing insertion hole 15d of partition board 15 while a hole 15b is made near the valve hole 14b through the inside face of said recess 15a. The bottom of said recess 15a is contacted against the delivery cover 16 to form a delivery chamber 16b with said chamber 16a and communicated through a communicating section 15c.