A pipeline A/D converter of the present invention includes a plurality of stages each operating for A/D conversion and a digital computing portion that outputs an A/D converted signal based on a digital signal output from each of the stages. In each of the stages, an analog signal from the preceding stage is sampled by passive elements C1 and C2 in a first period, and one of the passive elements is used as a feedback element in a second period to perform adding/subtracting with respect to the signal sampled by the other passive element. By the control from the digital computing portion, a test signal Tink is used instead of an analog output signal Vo(k-1), and a unique conversion-error value is detected and corrected based on the digital signal obtained by the operation of each of the stages. It is possible to obtain a high-resolution A/D convert that can suppress a conversion error caused by the relative error of capacitors used for analog signal processing without decreasing the speed of A/D conversion.