The present invention provides a row decoder of a semiconductor storage device that prevents an increase in a circuit area while maintaining a high operation speed. Namely, the row decoder of the semiconductor storage device includes a word line selection circuit that has voltage application MOS transistors for each of plural word lines, the voltage application MOS transistors applying a normal voltage to the word lines corresponding to memory cells selected among plural memory cells positioned at a portion where the plural word lines intersect plural bit lines in a predetermined normal operation, and applying a high voltage in a predetermined high voltage operation; and a level shift circuit that outputs the normal voltage or a ground voltage lower than the normal voltage in the normal operation, and that outputs the normal voltage or the high voltage in the high voltage operation, to the voltage application MOS transistor.