A hybrid working vehicle in which an engine is transversely disposed, comprising: a power unit including the engine, a generator-motor and a main hydraulic pump that are disposed in an engine room, the generator-motor and the main hydraulic pump being arranged linearly in this order or arranged in parallel with respect to the engine, the power unit being provided between a partition (10, 29a) which defines a border between a part of the hybrid working vehicle located in front of the engine room and the engine room, and a wall of a counterweight facing the engine room and located at a rear of the engine room; characterized in that the hybrid working vehicle comprises: a storage for storing electric power generated by the generator-motor, the storage being provided between the partition (10, 29a) and the wall and provided on at least one of: (i) a side of the power unit where the engine is arranged, and (ii) a side of the power unit where the main hydraulic pump is arranged; a cooling pump arranged to supply a cooling liquid for cooling the storage; and a radiator for cooling the cooling liquid for the storage, the radiator being independent of an engine radiator for cooling a cooling liquid for a cooling circuit connected to the engine, wherein the storage is cooled by the cooling liquid supplied from the radiator to the cooling pump. a power unit including the engine, a generator-motor and a main hydraulic pump that are disposed in an engine room, the generator-motor and the main hydraulic pump being arranged linearly in this order or arranged in parallel with respect to the engine, the power unit being provided between a partition (10, 29a) which defines a border between a part of the hybrid working vehicle located in front of the engine room and the engine room, and a wall of a counterweight facing the engine room and located at a rear of the engine room; characterized in that the hybrid working vehicle comprises: a storage for storing electric power generated by the generator-motor, the storage being provided between the partition (10, 29a) and the wall and provided on at least one of: (i) a side of the power unit where the engine is arranged, and (ii) a side of the power unit where the main hydraulic pump is arranged; a cooling pump arranged to supply a cooling liquid for cooling the storage; and a radiator for cooling the cooling liquid for the storage, the radiator being independent of an engine radiator for cooling a cooling liquid for a cooling circuit connected to the engine, a storage for storing electric power generated by the generator-motor, the storage being provided between the partition (10, 29a) and the wall and provided on at least one of: (i) a side of the power unit where the engine is arranged, and (ii) a side of the power unit where the main hydraulic pump is arranged; a cooling pump arranged to supply a cooling liquid for cooling the storage; and a radiator for cooling the cooling liquid for the storage, the radiator being independent of an engine radiator for cooling a cooling liquid for a cooling circuit connected to the engine, wherein the storage is cooled by the cooling liquid supplied from the radiator to the cooling pump.