The LED driving semiconductor apparatus for driving at least one LED includes an input terminal, an output terminal, a switching element block and a controller. The input terminal is connected to a high voltage side of a rectifying circuit for rectifying an alternating current voltage, and inputs the voltage from the rectifying circuit. The output terminal is provided for supplying a current to the LED. The switching element block is connected between the input terminal and the output terminal, and has a first switching element. The controller includes a regulator for generating a power source voltage for driving and controlling the switching element block, and a drain current detector for detecting a drain current of the switching element block, and performs on/off control of the first switching element to block the drain current of the switching element block when the drain current reaches a predetermined threshold.