A power conditioner 10 is provided with a maximum power follow-up control portion 12 for setting a DC operating voltage of a power converter 11, which converts output power of a power generator 2 into AC power, for making a power point corresponding to the output level of the power generator follow up with a maximum power point, and comprises an approximate function memory 25 for storing approximate functions related to the maximum power point, a follow-up control portion 34 for making the present power point reach proximate of the maximum power point on the basis of the approximate function, and a hill-climbing method follow-up control portion 35 for making the present power point reach the maximum power point by using a hill-climbing method when the present power point has reached proximate of the maximum power point.