In photodynamic therapy (PDT), an LD (61) for normal light emission is continuously turned on, while an LD (62) for excitation light emission is turned off. An electronic shutter of a CCD (21) is closed in a first half (A) of a frame (FR), and is opened in a second half (B) to capture a PDT image. An LD (63) for therapeutic light emission is turned on in synchronization with a start of the frame (FR), and is turned off in the middle of the second half (B). Due to an overlap period (T3) established between a therapeutic light irradiation period (T1) and a charge accumulation period (T2), the PDT image has an irradiation spot of the therapeutic light overlaid on a normal image. Thus, the PDT is carried out in short possible treatment time with checking on a monitor (22) whether or not the therapeutic light is applied to an appropriate position.
