To inexpensively provide an operation microscope device capable of sufficiently irradiating illumination light on an operated part without causing enlargement of the whole device.

The illumination light emitted from a light source 10 is divided in two to first illumination light and second illumination light by a semi- reflecting semi-transmissive member 14 of an illumination optical system 4, and the divided first illumination light is irradiated at an angle crossing an optical axis O of an objective lens 1. A second illumination light irradiating means 15 is provided for irradiating the second illumination light divided by the semi-reflecting semi-transmissive member 14 toward a crossing part of the first illumination light and the optical axis O of the objective lens 1. A light field moving means 19 for matching a crossing position of the first illumination light and the second illumination light with an observation visual field responding to a focal length of the objective lens 1 is interposed in an illumination light path between the light source 10 and the semi-reflecting semi- transmissive member 14.