A random number generator according to one embodiment includes a write circuit, a read circuit, and a signal output circuit. The write circuit inverts magnetization of a magnetic layer of a magnetic tunnel junction element stochastically by supplying current to the magnetic layer. The read circuit reads the magnetization. The signal output circuit generates a random number on the basis of the magnetization read by the read circuit. The random number generator includes a sequence control circuit that controls the write circuit and the read circuit. The sequence control circuit regulates the write circuit to supply the current to the write circuit in a first period, and causes the read circuit to read the magnetization after the first period is finished and then a second period longer than the first period is elapsed.