A lighting device, comprising: a switching power circuit for stepping down a DC input voltage (Vin) to a stepped-down DC voltage that is a rated voltage of a solid-state light emitting element that is a light source, wherein the switching power circuit comprises a switching element for controlling an output current provided by the switching power circuit to the solid-state light emitting element; and a controller for adjusting an average value of the output current flowing to said solid-state light emitting element to a value corresponding to a dimming level instructed from outside the lighting device by switching on and off, at a predetermined switching frequency, the switching element of said switching power circuit during applied times of successive intermittent periods, wherein each of said intermittent periods is defined by one of said applied times during which said controller switches the switching element on and off according to the predetermined switching frequency, followed by one stopped time during which said controller temporarily stops switching of the switching element, wherein a predetermined reference value is set to be less than an upper limit value for said average value corresponding to a highest dimming level, and to be more than a lower limit value for said average value corresponding to a lowest dimming level; and wherein said controller is configured to change said applied time of the intermittent periods while keeping the time period of said intermittent periods constant, when adjusting said average value of the output current flowing to said solid-state light emitting element to respective values within the range defined by the predetermined reference value and the upper limit value for said average value corresponding to a highest dimming level; and wherein said controller is further configured to change said stopped time in stages together with the time period of said intermittent periods while keeping said applied time of said intermittent periods constant and corresponding to said predetermined reference value, when adjusting said average value of the output current flowing to said solid-state light emitting element to respective values within the range defined by the lower limit value for said average value corresponding to a lowest dimming level and said predetermined reference value, excluding the predetermined reference value, wherein said constant applied time of said intermittent periods corresponds to a number of plural switching operations for the switching element. a switching power circuit for stepping down a DC input voltage (Vin) to a stepped-down DC voltage that is a rated voltage of a solid-state light emitting element that is a light source, wherein the switching power circuit comprises a switching element for controlling an output current provided by the switching power circuit to the solid-state light emitting element; and a controller for adjusting an average value of the output current flowing to said solid-state light emitting element to a value corresponding to a dimming level instructed from outside the lighting device by switching on and off, at a predetermined switching frequency, the switching element of said switching power circuit during applied times of successive intermittent periods, wherein each of said intermittent periods is defined by one of said applied times during which said controller switches the switching element on and off according to the predetermined switching frequency, followed by one stopped time during which said controller temporarily stops switching of the switching element, wherein a predetermined reference value is set to be less than an upper limit value for said average value corresponding to a highest dimming level, and to be more than a lower limit value for said average value corresponding to a lowest dimming level; and wherein said controller is configured to change said applied time of the intermittent periods while keeping the time period of said intermittent periods constant, when adjusting said average value of the output current flowing to said solid-state light emitting element to respective values within the range defined by the predetermined reference value and the upper limit value for said average value corresponding to a highest dimming level; and wherein said controller is further configured to change said stopped time in stages together with the time period of said intermittent periods while keeping said applied time of said intermittent periods constant and corresponding to said predetermined reference value, when adjusting said average value of the output current flowing to said solid-state light emitting element to respective values within the range defined by the lower limit value for said average value corresponding to a lowest dimming level and said predetermined reference value, excluding the predetermined reference value, wherein said constant applied time of said intermittent periods corresponds to a number of plural switching operations for the switching element.