Provided is a construction machine having a sufficient space for tool accommodation and allowing reducing agent to be supplied into a reducing-agent tank easily. The construction machine includes an engine, a reducing-agent tank having a tank body and a supply portion, and a tool box. The tool box includes a box body defining an accommodation space having an opening which opens the accommodation space outwards and allows a tool to be put into and taken from the accommodation space through the opening, and an opening/closing cover which opens and closes the opening. The tank body is outside the box body. The supply portion includes a basal end connected to the tank body and a distal end located in the accommodation space at a position making the distal end visible from the outside of the box body through the opening which is opened.