Excitation light λex is two-dimensionally scanned onto the living body tissue in the form of condensed light using an x-axis scanning mirror, a y-axis scanning mirror, and a condenser lens, whereby the excitation light λex is cast onto the living body tissue. This allows fluorescence observation with a relatively low output intensity of a laser light source. Furthermore, a white light image is generated by scanning the white light in the same way, thereby enabling fluorescence observation in the same observation region and at the same timing as with normal observation. This enables fluorescence observation of a sufficient area which allows the user to distinguish living body tissues in an endoscope observation image while suppressing deterioration in the laser light source.