To provide a cooler which cools a detector for detecting light or electromagnetic waves by a refrigerating machine, wherein vibrations generated from the refrigerating machine can be restricted from transmitting to a cooling object via a vacuum container, and also a thermal connection can be sufficiently insured between a cooling part and a cooling stage.

The cooler comprises a refrigerating machine support body 80 for supporting a GM refrigerator 70, a vacuum container support body 100 which is separated from the refrigerating machine support body 80 in view of vibrations for supporting a vacuum container 41, vacuum bellows 88 which connect the vacuum container 41 with the refrigerating machine support body 80, a plurality of flexible high heat conduction members 77 which thermally connect a first cooling part 73 with a first cooling stage 47, and a plurality of flexible high heat conduction members 84 which thermally connect a second cooling part 78 with a second cooling stage 50.