Semiconductor memory including a reference amplifier and a high-speed start-up circuit having four FETs. The reference amplifier supplies the reference voltage to a sense amplifier via a reference voltage supply line. The high-speed startup circuit has four FETs. The first FET is turned on to apply a first voltage onto a first line when the enable signal indicates deactivation. The second FET is turned on to apply ground potential onto the first line when the voltage on the reference voltage supply line is higher than a gate threshold voltage value. The third FET is turned on to generate the first voltage when the enable signal indicates activation. The fourth FET is turned off when the first line is at ground potential and is turned on to supply the first voltage from the third FET onto the reference voltage supply line when the first voltage is applied onto the first line.