Providing a screw compressor 1 having a lubricating oil system, the compressor being provided with a plurality of radial bearings 5 and a plurality of thrust bearings 6, a rotor shaft 2a or 3a is supported rotation-freely by each bearing, wherein at least one radial bearing 5 or at least one thrust bearing is provided with a hole space 25 or 34 with a bottom, the hole space being bored in the radial bearing and the thrust bearing so that a temperature-detecting terminal 26 is inserted in the hole space 25 or 34; at least one penetrating hole 28 or 35 is provided at the casing wall 1c of a casing that houses the radial bearing 5, so that the outside of the casing communicates with a space s1 for inserting the radial bearing, through the penetrating hole, the space s1 28 or 35 being formed inside of the casing wall; the temperature-detecting terminal 26 together with a sheath tube 27 is led into the space s1 through the penetrating hole 28 or 35.