An apparatus is realized which is capable of shortening the updating period of the measurement of a specific channel and lengthening the updating period of the measurement for another channel, thereby making the measurements for all the channels possible. The measurement apparatus includes a multiplexer that sequentially switches between analog input signals of a plurality of channels and internal calibration signals; an analog-to-digital converter that converts the signals from an analog to digital form; and a digital processor to which the signals are input, wherein the digital processor includes a sequence operation unit for sequentially switching between a combination of a channel for which a high-speed update is necessary and another channel, and the internal calibration signal among the input signals of the plurality of channels and supplying, to the multiplexer, an operation signal that is input to the AD converter.