An object of the present invention is to provide a chair-type phototherapy device that enables a patient to perform light irradiation accurately targeted at a treatment site in a seated position on a chair and consequently achieves effective phototherapy even when the treatment site is in the back region that the patient is unable to see, for example, as in light irradiation for dysuria patients and patients with pain, and the patient performs light irradiation by himself/herself at home. The present invention provides a chair-type phototherapy device having a seat on which a patient is seated. The chair-type phototherapy device includes a radiation module configured to emit radiation light toward a living body, a drive module positioned behind the patient for moving the radiation module, and a fixing module fixing the drive module to the seat.