A lighting apparatus for supplying power to a light source load, comprising: a switching element connected in series to a DC power supply and adapted to be controlled so as to be turned on and off at high frequency; an inductor through which a current flows from the DC power supply when the switching element is turned on, said inductor being connected in series to the switching element; a diode adapted to discharge electromagnetic energy stored in the inductor, when the switching element is turned on, to the light source load when the switching element is turned off, wherein the light source load comprises a semiconductor light emitting element; and a control circuit adapted to control an On and Off operation of the switching element, characterized in that: the control circuit comprises first, second and third control modes as control modes of the switching element, wherein the control circuit is adapted: (a), in the first control mode, to turn the switching element on and off at a predetermined oscillating frequency and an On time so that a current continuously flows through the inductor as a continuous mode without a sleep interval; (b), in the second control mode, to fix the oscillating frequency of the switching element and change the On time of the switching element; and (c), in the third control mode, to fix the On time of the switching element and change the oscillating frequency of the switching element, wherein a dimming range between a minimum dimming ratio and a maximum dimming ratio is divided into a plurality of intervals, and the second control mode and the third control mode are allocated for at least two intervals of the plurality of intervals, and wherein the control circuit is adapted: (i), if a full lighting mode is designated, to select the first control mode to fully light the light source load; and (ii), if a dimming ratio is designated, to select one of the second and third control modes according to the interval, to which the dimming ratio corresponds, to dim the light source load at the dimming ratio, wherein the control circuit is adapted to receive a dimming signal from outside to select the control mode of the switching element according to the dimming ratio determined by the dimming signal. a switching element connected in series to a DC power supply and adapted to be controlled so as to be turned on and off at high frequency; an inductor through which a current flows from the DC power supply when the switching element is turned on, said inductor being connected in series to the switching element; a diode adapted to discharge electromagnetic energy stored in the inductor, when the switching element is turned on, to the light source load when the switching element is turned off, wherein the light source load comprises a semiconductor light emitting element; and a control circuit adapted to control an On and Off operation of the switching element, characterized in that: the control circuit comprises first, second and third control modes as control modes of the switching element, wherein the control circuit is adapted: (a), in the first control mode, to turn the switching element on and off at a predetermined oscillating frequency and an On time so that a current continuously flows through the inductor as a continuous mode without a sleep interval; (b), in the second control mode, to fix the oscillating frequency of the switching element and change the On time of the switching element; and (c), in the third control mode, to fix the On time of the switching element and change the oscillating frequency of the switching element, (a), in the first control mode, to turn the switching element on and off at a predetermined oscillating frequency and an On time so that a current continuously flows through the inductor as a continuous mode without a sleep interval; (b), in the second control mode, to fix the oscillating frequency of the switching element and change the On time of the switching element; and (c), in the third control mode, to fix the On time of the switching element and change the oscillating frequency of the switching element, wherein a dimming range between a minimum dimming ratio and a maximum dimming ratio is divided into a plurality of intervals, and the second control mode and the third control mode are allocated for at least two intervals of the plurality of intervals, and wherein the control circuit is adapted: (i), if a full lighting mode is designated, to select the first control mode to fully light the light source load; and (ii), if a dimming ratio is designated, to select one of the second and third control modes according to the interval, to which the dimming ratio corresponds, to dim the light source load at the dimming ratio, (i), if a full lighting mode is designated, to select the first control mode to fully light the light source load; and (ii), if a dimming ratio is designated, to select one of the second and third control modes according to the interval, to which the dimming ratio corresponds, to dim the light source load at the dimming ratio, wherein the control circuit is adapted to receive a dimming signal from outside to select the control mode of the switching element according to the dimming ratio determined by the dimming signal.