A light-emitting diode driving apparatus, comprising: a switching transistor (Tr) which has a first terminal electrically connected with a power source and becomes an on-state or an off-state in response to a pulse width modulation signal applied to a control terminal; a light=emitting diode which is electrically connected with a second terminal of the switching transistor (Tr) and emits light when an electric current flows; a first comparison circuit which is electrically connected between the switching transistor (Tr) and the light-emitting diode and outputs a first voltage depending on a result of comparison between a first input voltage corresponding to a voltage applied to the light-emitting diode and a first threshold voltage; a second comparison circuit which is electrically connected between the switching transistor (Tr) and the light-emitting diode and outputs a second voltage depending on a result of comparison between a second input voltage corresponding to a voltage applied to the light-emitting diode and a second threshold voltage different from the first threshold voltage; characterized by a signal processing circuit configured to detect a failure having occurred in the light-emitting diode on the basis of an output state of the pulse width modulation signal and a combination of respective voltage levels of the first voltage, the second voltage and a third voltage on the second terminal of the switching transistor (Tr), wherein the signal processing circuit is configured to detect that the combination of the respective voltage levels is different from a combination of the respective voltage levels when no failure occurs in the light-emitting diode, in a case where the output state of the pulse width modulation signal is the state where the pulse width modulation signal for making the light-emitting diode emit light is being output, and thereby detects the failure in the light-emitting diode. a switching transistor (Tr) which has a first terminal electrically connected with a power source and becomes an on-state or an off-state in response to a pulse width modulation signal applied to a control terminal; a light=emitting diode which is electrically connected with a second terminal of the switching transistor (Tr) and emits light when an electric current flows; a first comparison circuit which is electrically connected between the switching transistor (Tr) and the light-emitting diode and outputs a first voltage depending on a result of comparison between a first input voltage corresponding to a voltage applied to the light-emitting diode and a first threshold voltage; a second comparison circuit which is electrically connected between the switching transistor (Tr) and the light-emitting diode and outputs a second voltage depending on a result of comparison between a second input voltage corresponding to a voltage applied to the light-emitting diode and a second threshold voltage different from the first threshold voltage; characterized by a signal processing circuit configured to detect a failure having occurred in the light-emitting diode on the basis of an output state of the pulse width modulation signal and a combination of respective voltage levels of the first voltage, the second voltage and a third voltage on the second terminal of the switching transistor (Tr), wherein the signal processing circuit is configured to detect that the combination of the respective voltage levels is different from a combination of the respective voltage levels when no failure occurs in the light-emitting diode, in a case where the output state of the pulse width modulation signal is the state where the pulse width modulation signal for making the light-emitting diode emit light is being output, and thereby detects the failure in the light-emitting diode.