A code generating apparatus comprises an oscillator for continuously producing a sinusoidal wave which has a constant frequency, a square wave generating circuit supplied with the output sinusoidal wave of the oscillator, for generating first and second square waves having period which is twice the period of the sinusoidal wave, where the first and second square waves having mutually inverted phases, a code transmitting circuit pre-stored with a code which is to be generated, as a bit sequence, for alternately transmitting through first and second output terminals thereof the bit sequence in terms of one bit in phase with the first or second square wave, a switching signal producing circuit for producing a switch signal from a combination of the first and second square waves and output signals from the first and second output terminals of the code transmitting circuit, and a switching circuit controlled in response to the switching signal from the switching signal producing circuit, for selectively and intermittently producing through a code output terminal thereof the output sinusoidal wave of the oscillator as the code.