The present invention aims to provide an exhaust purification system capable of clearing blockage soon after start-up in a reducing agent injection valve caused by the solidification of an aqueous urea solution, and preventing the decline of exhaust purification efficiency at the time of start-up of an internal combustion engine. The exhaust purification system is provided with a DPF, a reducing agent injection valve, and an SCR catalyst in order from the exhaust upstream side, and is provided with: an operation state detection unit capable of detecting the start-up and stoppage of an internal combustion engine; a forced regeneration control unit for performing a forced regeneration of the DPF; a condition establishment determination unit for determining whether there is a risk of solidification of an aqueous urea solution when the operation state detection unit detects that the internal combustion engine has stopped; a data storage unit for storing the determination result from the condition establishment determination unit as data; and a blockage-clearing control unit for controlling a temperature-raising means for raising the temperature of the reducing agent injection valve, on the basis of the data, at the time of start-up of the internal combustion engine, and raising the temperature of the reducing agent injection valve.