PURPOSE: To shorten a time in which a predetermined stable running condition in starting is reached without degrading an oil separating function by affording communication between a muffler chamber of a rotary compressor element and a bypass path bypassing a gap path of a motor element.

CONSTITUTION: When a discharged refrigerant temperature is lower than the condensing point in starting and a switch device 25 is opened, discharged refrigerant passes through a bypass path 23 without passing through other gap paths 5, 6, 8. The discharged refrigerant can be prevented from liquefaction due to the endothermic action of a motor element 1 having a large thermal capacity and from reduction of a discharge amount of gas refrigerant in a discharge pipe 22 by liquefied amount, so that a rise time in which a predetermined stable running condition is reached is shortened. Also, since the circulating refrigerant does not pass through the gap paths 5, 6, 8 as oil separating paths in the starting, the abnormal increase of an oil mix amount can be prevented by separating the mixed oil through an oil discharge path 30 in a muffler chamber 18 of a circulating path.