To provide a compact electron tube device with stem pins, in which the photoelectric surface is efficiently cooled, and dew condensation is prevented, further operability is improved.

A photomultiplier tube 10 and a Peltier element 30 cooling a photoelectric surface 12 are set in a housing 20. The housing 20 is composed of a case 21 and a socket part 23, and the photomultiplier tube 10 is fixed and held by the socket part 23 through stem pins. The Peltier element 30 is held by pressing against the case 21 by the socket part 23 and the photomultiplier tube 10. Further, the housing 20 is kept airtight, and xenon gas is enclosed in it. The constitution like this keeps thermal contact of the photomultiplier tube 10 with the outside to a minimum, to cool the photoelectric surface 12 efficiently, and the simplified constitution realizes miniaturization and a low cost of the device.