An exhaust emission control device reduces nitrogen oxide included in exhaust air from an internal combustion engine. The device includes an exhaust pipe, a catalyst, a supply device, a tank, and a temperature regulating device. The exhaust pipe defines a passage for exhaust air discharged from the engine. The catalyst is disposed in the exhaust pipe. The catalyst is capable of promoting reduction reaction of the nitrogen oxide in exhaust air. The supply device is for supplying a fluid-state additive agent, which is used for the reduction reaction, to an upstream side of the catalyst in a flow direction of exhaust air. The additive agent is stored in the tank. The temperature regulating device is for regulating temperature of the additive agent, which is supplied by the supply device, to be in a predetermined range.