An exhaust emission purifying apparatus comprising: a reduction catalytic converter that is disposed in an engine exhaust pipe for reductively purifying nitrogen oxides in an exhaust emission using a reducing agent supplied from a reducing agent container; a concentration sensor that detects a concentration of the reducing agent stored in the reducing agent container; a residual amount sensor that detects that a residual amount of the reducing agent stored in the reducing agent container becomes equal to or smaller than a predetermined amount; and a control unit incorporating therein a computer, wherein the control unit executes: a reducing agent judging process of judging that a liquid in the reducing agent container is any different kind of aqueous solution or that the reducing agent is deficient, when the concentration of the reducing agent detected by the concentration sensor deviates from a predetermined range or when it is detected by the residual amount sensor that a residual amount becomes equal to or smaller than a predetermined amount; and an engine control process of inhibiting restarting of an engine operation, when such an initial judgment is made by the reducing agent judging process that the liquid in the reducing agent container is the different kind of aqueous solution or the reducing agent is deficient and also when such a subsequent judgment is made that a traveling distance of a vehicle driven by the engine after the initial judgment is equal to or longer than a predetermined distance, while permitting the restarting of the engine operation for rest conditions, wherein the control unit further executes an operation stop intention judging process of judging whether or not the engine operation is stopped unintentionally, and the engine control process permits the restarting of the engine operation when the operation stop intention judging process judges that the engine operation is stopped unintentionally, and the operation stop intention judging process executed by the control unit judges that the engine operation is unintentionally stopped when an elapsed time until the restarting of the engine operation is performed from a time when the engine operation is stopped is less than a predetermined time, or the operation stop intention judging process executed by the control unit judges that the engine operation is unintentionally stopped when a difference between an engine temperature detected at a time when the engine operation is stopped and that detected at a time when the restarting of the engine operation is performed is less than a predetermined temperature. a reducing agent judging process of judging that a liquid in the reducing agent container is any different kind of aqueous solution or that the reducing agent is deficient, when the concentration of the reducing agent detected by the concentration sensor deviates from a predetermined range or when it is detected by the residual amount sensor that a residual amount becomes equal to or smaller than a predetermined amount; and an engine control process of inhibiting restarting of an engine operation, when such an initial judgment is made by the reducing agent judging process that the liquid in the reducing agent container is the different kind of aqueous solution or the reducing agent is deficient and also when such a subsequent judgment is made that a traveling distance of a vehicle driven by the engine after the initial judgment is equal to or longer than a predetermined distance, while permitting the restarting of the engine operation for rest conditions, wherein the control unit further executes an operation stop intention judging process of judging whether or not the engine operation is stopped unintentionally, and the engine control process permits the restarting of the engine operation when the operation stop intention judging process judges that the engine operation is stopped unintentionally, and the operation stop intention judging process executed by the control unit judges that the engine operation is unintentionally stopped when an elapsed time until the restarting of the engine operation is performed from a time when the engine operation is stopped is less than a predetermined time, or the operation stop intention judging process executed by the control unit judges that the engine operation is unintentionally stopped when a difference between an engine temperature detected at a time when the engine operation is stopped and that detected at a time when the restarting of the engine operation is performed is less than a predetermined temperature.