In a battery charge indicating system, there are provided detecting means of an npn-transistor for detecting a closed condition of an ignition switch, and switching means of a pnp-transistor for supplying a base current to a driving transistor in response to an output of the detecting means, so that the driving transistor is made conductive when the ignition switch is closed and a generator is not generating its output. The emitter of the pnp-transistor is connected to a battery not through a current supply terminal for a voltage regulator, whereby even when the current supply terminal is accidentally disconnected from the regulator, the driving transistor is made conductive so that an indicating lamp is activated to indicate that the generator is not in the operation condition.