A solid-state image pickup apparatus includes: an image pickup portion in which are arranged a plurality of pixels with a photo-electric conversion element, the pixels which generate and output a signal in accordance with the intensity of an incident electromagnetic wave; a frequency conversion portion that includes a link circuit in which a plurality of inversion circuits with a first terminal and a second terminal are linked in a ring, each of the inversion circuits having a varying delay time from an input signal to an output signal based on the voltage difference between the voltage supplied to the first terminal and the voltage supplied to the second terminal, and the frequency conversion portion which generate clock pulses at a frequency based on the voltage difference; a count portion which counts the clock pulses generated by the frequency conversion portion; and a transistor including: a third terminal to which is input a predetermined voltage; a fourth terminal connected to the first terminals; and a fifth terminal to which are input signals from the pixels, the transistor controlling a current that is passed between the third terminal and the fourth terminal based on a signal that is input to the fifth terminal.