provided for driving second drive shaft 33 of second compression mechanism 3 electric motor 35 has a rotor 36 which is fixed to second drive shaft 33 and a stator 37 stator 37 is disposed within stator housing 38 and motor 35 also is accommodated within stator housing 38 in second compression mechanism 3 refrigerant gas is introduced from inlet port 18 to first inlet chamber 20 and flows into a second inlet chamber 40 of second compressing mechanism 3 through a communicating path 39 refrigerant gas then is introduced to second fluid pockets 32 of second compression mechanism 3 fluid pockets 32 move toward the center of second fixed scroll 30 while being reduced in volume consequently the refrigerant gas in fluid pockets 32 is compressed the compressed refrigerant gas is discharged into a second discharge path 42 through a second discharge port 41 formed within a valve plate of the fixed scroll 30 the discharged refrigerant then flows out to a high pressure side of an external refrigerant circuit through outlet port 23 in a preferred embodiment of the present invention first fixed scroll 10 of first compression mechanism 2 and second fixed scroll 30 of first compression mechanism 3 are disposed back to back e g.