A construction machine, comprising: an engine; a reducing-agent tank including a tank body which stores reducing agent for reducing exhaust gas of the engine, and a supply portion which is connected to the tank body to allow the reducing agent to be supplied into the tank body through the supply portion; and a tool box for accommodating a tool, the tool box including a box body internally defining an accommodation space having an opening which allows the accommodation space to be opened outwards of the box body and which allows the 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, wherein: the supply portion includes a basal end connected to the tank body and a distal end opposite to the basal end, characterized in that the tank body is disposed outside the box body, the distal end of the supply portion is located at a position in the accommodation space, and the position makes the distal end visible from the outside of the box body through the opening which is opened, wherein the box body includes a rear wall adjacent to the tank body, and the supply portion passes through the rear wall to locate the distal end of the supply portion in the accommodation space, and the tank body includes a front wall adjacent to the rear wall, and the basal end of the supply portion is directly connected to the front wall of the tank body. an engine; a reducing-agent tank including a tank body which stores reducing agent for reducing exhaust gas of the engine, and a supply portion which is connected to the tank body to allow the reducing agent to be supplied into the tank body through the supply portion; and a tool box for accommodating a tool, the tool box including a box body internally defining an accommodation space having an opening which allows the accommodation space to be opened outwards of the box body and which allows the 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, wherein: the supply portion includes a basal end connected to the tank body and a distal end opposite to the basal end, characterized in that the tank body is disposed outside the box body, the distal end of the supply portion is located at a position in the accommodation space, and the position makes the distal end visible from the outside of the box body through the opening which is opened, wherein the box body includes a rear wall adjacent to the tank body, and the supply portion passes through the rear wall to locate the distal end of the supply portion in the accommodation space, and the tank body includes a front wall adjacent to the rear wall, and the basal end of the supply portion is directly connected to the front wall of the tank body. the supply portion includes a basal end connected to the tank body and a distal end opposite to the basal end, characterized in that the tank body is disposed outside the box body, the distal end of the supply portion is located at a position in the accommodation space, and the position makes the distal end visible from the outside of the box body through the opening which is opened, wherein the box body includes a rear wall adjacent to the tank body, and the supply portion passes through the rear wall to locate the distal end of the supply portion in the accommodation space, and the tank body includes a front wall adjacent to the rear wall, and the basal end of the supply portion is directly connected to the front wall of the tank body.