Abstract: A lamp failure detecting device for automobile consists of a lamp circuit including a plurality of lamps connected in parallel, a current-detecting resistance connected to a power-supply source through the lamp circuit in series, a first voltage divider circuit including resistances to which a voltage divided by the current detecting resistance and the lamp circuit is applied a second voltage divider circuit including resistances to which a voltage supplied from the power-supply source is applied and a comparator circuit comparing the difference between the divided voltages in the voltage divider circuits to produce a a failure detection signal. Diodes are provided in the first and second voltage divider circuits respectively in the forward direction. Non-linearity of the current flowing through the lamps for the change of the power-supply voltage is corrected by the diodes.