A random number sequence generation apparatus includes: a semiconductor laser device repeatedly generating a pulsed laser beam having a disordered phase; an interferometer including a first transmission line and a second transmission line, a first port connected to an input terminal side and to which the pulsed laser beam is input, a second port connected to an output terminal side and outputs the pulsed laser beam, and a third port connected to the input terminal side; a Faraday mirror connected to the second port and reflecting the pulsed laser beam; a photodiode connected to the third port and outputs an electrical signal in accordance with interference light of the pulsed laser beam that is reflected by the Faraday mirror and passes through one of the transmission lines; and an AD converter configured to generate a random number sequence on the basis of the electrical signal and a threshold.