A data readout circuit including a 1st PMOS transistor operating in saturation and including a source connected to a power supply, a drain connected to an input terminal a memory cell, and a gate connected to a 1st bias voltage; a 2nd PMOS transistor including a source connected to the drain of the 1st PMOS transistor, a drain connected to an output terminal, and a gate connected to a 2nd bias voltage; a 1st NMOS transistor including a drain connected to the drain of the 2nd PMOS transistor, a source grounded, and a gate connected to a 3rd bias voltage; and a bias voltage section causing the 2nd PMOS transistor to operate in saturation, and supplying the 2nd bias voltage adjusted so as to keep a reference voltage of the input terminal at a junction point between the drain and the source of the 1st and 2nd PMOS transistors respectively.