Provided are a flash memory device and method of controlling certain program operation voltages. The flash memory device includes a high voltage generation circuit providing a high voltage to a block selection circuit and a program voltage to a row decoder. The high voltage generation circuit includes a charge pump, a high voltage control circuit controlling the charge pump to provide the high voltage, and a program voltage control circuit providing the program voltage in relation to the high voltage, wherein the high voltage control circuit and the program voltage control circuit operate in response to the same control code.