A successive approximation type analog-to-digital (AD) converter includes: a converting and comparing section configured to compare an input analog signal and an analog signal as an analog conversion result of a digital data; and a successive approximation section configured to change the digital data based on the comparison result by the converting and comparing section. The converting and comparing section includes: a DA (digital-to-analog) section configured to perform an analog conversion on the digital data of a predetermined number of bits in an ordinary mode, and on the digital data of bits smaller than the predetermined number of bits in a test mode.