PURPOSE: To supply a self-clocked signal which bootstraps a work line in a very short period.

CONSTITUTION: An address signal generated from address bits A1 and A2 and clock signals Y and Z are inputted to each clock generator 20. A bootstrap enable signal BEBAR outputted from a row address decoder 22 is inputted also to each clock generator 20. Signals 1 to 4 outputted from clock generators 20 are inputted to the row address decoder 22. An address signals generated from address bits A3 to A8 and a clock signal X are inputted also to the row address decoder 22. The row address decoder 22 selectively outputs work line signals WL0 to WL255.