A semiconductor device is disclosed, which relates to a technology for a sense-amplifier (sense-amp) configured to compensate for mismatch of a sensing bit-line. The semiconductor device includes a sense-amplifier configured to selectively control connection between a pair of bit lines and a pair of sensing bit lines in response to a connection control signal in an offset compensation period, and precharge a pull-down power-supply line with a bit line precharge voltage level in the offset compensation period. The semiconductor device also includes a pull-down voltage controller configured to increase a voltage of the pull-down power-supply line by a predetermined level in response to a pull-down control signal in the offset compensation period.