To provide a medical energy irradiation apparatus which, having a simple and inexpensively manufacturable structure, enables a doctor using it in the heat curing of prostatic hypertrophy or the like to accurately and stably irradiate a prescribed site deep in a living body with a laser beam and, even if its observation window is smeared, to observe tissues of a living body. An inserting portion of the medical energy irradiation apparatus to be inserted into a living body according to the invention has an emitting portion for emitting a laser beam toward tissues of the living body; an observation window, provided near the tip of the inserting portion in its inserting direction, for observing the tissues of the living body; and a hollow pipe for supporting a supporting member, which supports the emitting portion, shiftably in the lengthwise directions of the inserting portion and feeding detergent to the observation window. Therefore, when the observation window is smeared, detergent can be fed to the observation window to remove the smear of the observation window.