The present invention provides a semiconductor memory and a control method therefor, the semiconductor device including a first current-voltage conversion circuit connected to a core cell provided in a nonvolatile memory cell array, a second current-voltage conversion circuit connected to a reference cell through a reference cell data line, a sense amplifier sensing an output from the first current-voltage conversion circuit and an output from the second current-voltage conversion circuit, a compare circuit comparing a voltage level at the reference cell data line with a predefined voltage level, and a charging circuit charging the reference cell data line, if the voltage level at the reference cell data line is lower than the predefined voltage level during pre-charging the reference cell data line. According to the present invention, the pre-charging period of the reference cell data line can be shortened, and the data read time can be shortened.