Two sets of assemblies are arranged such that a diesel particulate filter device of an assembly as a first set, a selective catalytic reduction device of the assembly as the first set, a selective catalytic reduction device of an assembly as a second set, and a diesel particulate filter device of the assembly as the second set are located next to each other in this order. Respective first and second connection pipes are routed through a region directly underneath an arrangement region where the two selective catalytic reduction devices and the like are arranged, and connected to the respective diesel particulate filter devices. Thereby, an engine unit and a work vehicle which facilitate connection between an engine and an exhaust gas treatment structure and can reduce a load on the first and second connection pipes due to vibration can be achieved.