An inspection apparatus includes: beam generation means for generating any of charged particles and electromagnetic waves as a beam; a primary optical system that guides the beam into an inspection object held in a working chamber and irradiates the inspection object with the beam; a secondary optical system that detects secondary charged particles occurring from the inspection object; and an image processing system that forms an image on the basis of the detected secondary charged particles. The primary optical system includes a photoelectron generator having a photoelectronic surface. The base material of the photoelectronic surface is made of material having a higher thermal conductivity than the thermal conductivity of quartz.