A signal reading method successively outputs a read signal by scanning a voltage value of an integrating capacitor in an image sensor in which a plurality of sensor parts are arranged in a two-dimensional array made up of rows and columns and each sensor part includes the integrating capacitor accumulating a charge obtained by integrating a photocurrent output from a sensor. A first integration of the photocurrent using the integrating capacitor and a first sampling and holding using a sample and hold capacitor are performed in a first time interval, during a time of one frame made up of the first through third time intervals. A second integration of the photocurrent using the integrating capacitor is performed in the second time interval, and processes in the first and second time intervals are performed in common with respect to all of the sensor parts simultaneously. A vertical scan is started by selecting the row in an order starting from a first row.