A detector for detecting sulfur components comprising a storage portion for storing SOx and NOx in the exhaust gas passing through an exhaust passage, in which the more an amount of stored SOx increases, the more an amount of stored NOx decreases, and which does not release SOx but release NOx at a set temperature, and a temperature sensor, estimating said amount of stored SOx on the basis of a relationship between, after said storage portion becomes said set temperature by heating, a heating pattern of said storage portion and temperature change of said storage portion measured by said temperature sensor, and detecting an integrated amount of SOx passing through said exhaust passage during a given period or an value on the basis of said integrated amount.