To calculate a highly precise characteristic value of a pump without previously measuring operating characteristic data of the pump.

There provided are a reference operation point specifying section 16A for calculating a reference flow rate Q0 or a reference pump head H0 by specifying a reference operation point R0 that is an intersecting point of a resistance curve C and a reference pump head curve A0 based on an arbitrary characteristic value, and a reference power point specifying section 16B for calculating the reference flow rate Q0 or a reference shaft power E0 by specifying a reference power point P0 that is an intersecting point of a shaft power curve at control B1 and a reference shaft power curve B0 based on the arbitrary characteristic value. A characteristic value calculation section 16C calculates a desired unknown characteristic value as an output characteristic value by successively calculating the characteristic values at the reference operation point R0 and the reference power point P0 by the reference operation point specifying section 16A and the reference operation point specifying section 16A based on an input characteristic value.