Transmission of vibration from an engine to a cab is suppressed. An upper slewing body includes a slewing frame, an engine deck, a cab deck, a tank deck, and a vibration transmission regulating unit. The tank deck is arranged on the more laterally outer side than the slewing frame and is fixed to the slewing frame. The tank deck is arranged forward of the engine deck and is arranged rearward of the cab deck. The vibration transmission regulating unit is provided between the engine deck and the tank deck to regulate direct transmission of vibration from the engine deck to the tank deck, the vibration occurring as the engine operates.