A compound microscope device allowing simultaneous observation of one specimen by a transmission electron microscope and an optical microscope, is provided. A compound microscope device 1 of the present invention has a transmission electron microscope 2 and an optical microscope 4. A specimen 10 and a reflection mirror 41 are disposed on an electron optical axis C of an electron ray. The reflection mirror 41 is inclined from the electron optical axis C toward the optical object lens 43 and the specimen 10. Light from the specimen 10 (fluorescent light, reflection light, and the like) is reflected by the reflection mirror 41 and entered into the optical object lens 43. The electron ray from the electron microscope 2 passes through a mounting center hole 42 of the reflection mirror 41. This makes it possible to observe one specimen simultaneously by the electron microscope 2 and the optical microscope 4.