The present invention provides a controller for a pendulum type wave-power generating apparatus. Electric power produced by wave-power generation has been pointed out as being of low efficiency and more expensive than wind-power generation. To overcome the above problems, the present invention uses resonance and impedance matching of the sea waves, thus making it possible to markedly enhance the efficiency of wave-power generation. The present invention does not use a wave-height meter which is generally expensive and controls the generating apparatus in response to variation of the conditions of the sea, thus automatically maintaining the resonance and impedance matching operation, thereby making high-efficiency operation possible. As a result, the cost of the wave-power generation can be reduced, so that the wave-power generation can be widely commercialized.