A compound microscope device comprising: a transmission electron microscope including an electron gun that releases an electron ray toward a specimen, an electromagnetic object lens that images the electron ray, and a detection part in into which the electron ray having passed through the electromagnetic object lens is entered; characterised in that the compound microscope further comprises: an incident-light fluorescent microscope including a light source that emits excitation light to irradiate the specimen, a light object lens that collects fluorescent light emitted from the specimen, and a light detection part into which the fluorescent light is entered; and a reflection mirror including a mounting center hole larger in diameter than a beam diameter of the electron ray, wherein the electromagnetic object lens is formed by a cylindrical coil and a yoke covering the coil, the yoke has a notch, wherein the portion of the yoke having the notch constitutes a pole piece, the reflection mirror is disposed on an electron-optical path between upper and lower poles of the pole piece, the electron ray passes through the mounting center hole of the reflection mirror, the excitation light is reflected by the reflection mirror toward the specimen, the fluorescent light is reflected by the reflection mirror toward the light object lens, electron ray irradiation and excitation light irradiation are coaxially performed on the specimen, and simultaneous observation is possible by the electron microscope and the fluorescent microscope. a transmission electron microscope including an electron gun that releases an electron ray toward a specimen, an electromagnetic object lens that images the electron ray, and a detection part in into which the electron ray having passed through the electromagnetic object lens is entered; characterised in that the compound microscope further comprises: an incident-light fluorescent microscope including a light source that emits excitation light to irradiate the specimen, a light object lens that collects fluorescent light emitted from the specimen, and a light detection part into which the fluorescent light is entered; and a reflection mirror including a mounting center hole larger in diameter than a beam diameter of the electron ray, wherein the electromagnetic object lens is formed by a cylindrical coil and a yoke covering the coil, the yoke has a notch, wherein the portion of the yoke having the notch constitutes a pole piece, the reflection mirror is disposed on an electron-optical path between upper and lower poles of the pole piece, the electron ray passes through the mounting center hole of the reflection mirror, the excitation light is reflected by the reflection mirror toward the specimen, the fluorescent light is reflected by the reflection mirror toward the light object lens, electron ray irradiation and excitation light irradiation are coaxially performed on the specimen, and simultaneous observation is possible by the electron microscope and the fluorescent microscope. an incident-light fluorescent microscope including a light source that emits excitation light to irradiate the specimen, a light object lens that collects fluorescent light emitted from the specimen, and a light detection part into which the fluorescent light is entered; and a reflection mirror including a mounting center hole larger in diameter than a beam diameter of the electron ray, wherein the electromagnetic object lens is formed by a cylindrical coil and a yoke covering the coil, the yoke has a notch, wherein the portion of the yoke having the notch constitutes a pole piece, the reflection mirror is disposed on an electron-optical path between upper and lower poles of the pole piece, the electron ray passes through the mounting center hole of the reflection mirror, the excitation light is reflected by the reflection mirror toward the specimen, the fluorescent light is reflected by the reflection mirror toward the light object lens, electron ray irradiation and excitation light irradiation are coaxially performed on the specimen, and simultaneous observation is possible by the electron microscope and the fluorescent microscope.