In a non-volatile memory capable of electrically rewriting data, a timer circuit for determining writing time that is operable at any time at a voltage of under 1.0 V. The timing circuit has a regulated voltage circuit for outputting a regulated output voltage no greater than 1.0 V, a constant current circuit for producing a constant current having a value determined by the regulated output voltage, a voltage comparing circuit for comparing an input voltage input to one terminal with a reference voltage input to another terminal, and a capacitive element connected to a constant current output terminal of the constant current circuit. A connecting point of the constant current output terminal of the constant current circuit and the capacitive element is connected as the input voltage to the voltage comparing circuit, so that a desired time period is determined by comparing a voltage to the terminal of the voltage comparing circuit connected to the capacitive element with the reference voltage connected to the other terminal of the comparing circuit.