PURPOSE: To provide a mass center calculation circuit for calculating the center position X among plural pieces of distributed mass.

CONSTITUTION: A binary weighting numbers are given to respective (n) capacitor arrays ARRAY by respective (m) capacitors Co, it is determined by a binary word Bi of (m) bits whether the respective capacitors Co are related to sampling or not and during a term Ti, input voltages Vhi-Vhn are sampled from the arrays but during a term T2, sampled values are added and transferred to a feedback capacitor 29 at an operational amplifier 30 so that a reference voltage VR can be generated. During a term T3, (n) pieces of input voltages Vhi-Vhn are sampled again from the arrays, during terms T4 and T4+m-1, the digital weighting of binary word Bi is set to a continuous approximate register 22 by the reference voltage VR and at the end of the term T4+m-1, a digital word expressing the central position X is outputted.