To rapidly and precisely calculate the amount of cuts of toxic substances contained in exhaust gas.

This system or method for calculating the amount of cuts of toxic substances comprises a detecting means 21 for receiving the position information of a vehicle and the operating state of the vehicle; a moving route recording means 23 for receiving and recording the traveling route of the vehicle transmitted from the detecting means 31, an exhaust gas emission calculating means 25 for calculating exhaust gas emission based on the traveling route and vehicle data, an estimation means 27 for estimating the average moving route and moving time when traveling without receiving a route guide, an average exhaust gas emission calculating means 29 for calculating the average exhaust gas emission determined by the estimation means 27, and a calculation means 31 for calculating the effect of reducing the toxic substances contained in exhaust gas by the route guide by the calculation means 29 and 25. The computer program and the transaction method of amount of cuts of toxic substances are for executing this method or system.