A construction machine includes a substantially vertical firewall located in front of an engine, which is mounted to a main swing frame of the machine. The firewall may include a plurality of partition plates, and a plurality of elastically deformable protruding plates connected along lower ends of the partition plates. A lateral plate connected to a bottom plate of the swing frame may be fitted between the elastically deformable protruding plates and the lower ends of the partition plates to fix the lower ends of the partition plates to the main swing frame of the machine. The lateral plate may be located in front of a lower part of the engine.