A power-on read circuit includes a power voltage detector, a first voltage booster, a voltage selector, a reference voltage generator and a read voltage generator. The power voltage detector detects a power voltage to generate a control signal. The first voltage booster generates a first boosted voltage according to the control signal. The voltage selector selects the power voltage or the first boosted voltage to generate a selected voltage. The reference voltage generator receives the selected voltage as an operating power source, and generates a reference voltage based on the selected voltage according to the control signal. The read voltage generator generates a second boosted voltage according to the reference voltage and a clock signal, and generate a read voltage based on the second boosted voltage according to the control signal. The read voltage is provided to a memory cell array to perform a data reading operation.