An apparatus for estimating the lifetime of a surge protective device (SPD) using the discharge characteristics of a metal oxide varistor (MOV) includes an MOV having an input terminal and an output terminal; an impulse voltage application unit applying an impulse voltage for MOV test to the input terminal of the MOV; a discharge current measurement unit; a first switching unit connecting a power line to the input terminal of the MOV; a second switching unit connecting a ground line to the output terminal of the MOV in the normal mode and selectively connecting the discharge current measurement unit in the MOV test mode; an MOV test management unit providing information; a discharge current check unit generating an MOV abnormal signal; and an MOV state display unit displaying an MOV abnormal signal.