<p>In the present invention, a lighting device comprises the following: a light-emitting element (4); a constant current circuit (2) for supplying the light-emitting element with a constant current; a switching element (6) for switching the current flowing through the light-emitting element; and a control circuit (100) which supplies a drive signal to the switching element in order to control switching by the switching element, changes the duty ratio of the drive signal in order to change the luminance of the light-emitting element, and changes the frequency of the drive signal if the duty ratio is small so that the frequency of the drive signal becomes higher than when the duty ratio is large.</p>
