A semiconductor device may include a power supply circuit, a word line control circuit, and a memory circuit. The power supply circuit may drive a pre-charge voltage to a level of an external voltage based on a write initialization signal which is enabled if a command has a predetermined level combination. The word line control circuit may generates two or more word line selection signals that are sequentially counted based on the write initialization signal. The memory circuit may sequentially select a plurality of word lines based on the word line selection signals. The memory circuit may drive bit lines of memory cells connected to the selected word line to the pre-charge voltage. The memory circuit may store data, which are loaded on the bit lines to have a level of the pre-charge voltage, into the memory cells connected to the selected word line.