A lighting system includes: an illumination light source which irradiates a user with illumination light； a user interface which receives a user operation； a controller which controls an amount of light of the illumination light source and an irradiation period of the illumination light source； and a storage which stores characteristic information having a negative correlation between the amount of light and the irradiation period. When the user interface receives a user operation which specifies a value of one of the amount of light and the irradiation period, the controller determines a value of the other according to the characteristic information and controls the illumination light source according to the specified value of the one of the amount of light and the irradiation period and the determined value of the other.
