Provided is a semiconductor device determining connection status between an output terminal connected to an output buffer and an external device, the semiconductor device including a test voltage generating circuit to generate test voltage for changing voltage of the output terminal, a connection detection determining circuit to compare voltage of the output terminal with reference voltage and to determine connection status of the external device based on the comparing result, and a compensation circuit generating simulation current where leak current generated at the output buffer is reproduced in a simulatory manner and compensating voltage change of the output terminal by the simulation current.