An evaporated fuel treatment device for a motorcycle characterized by comprising: a fuel tank which is arranged below a rider's seat and is supported on a vehicle body frame; a power unit which includes an engine generating power for driving a rear wheel, is swingably supported on the vehicle body frame; and a charge pipe passage which introduces a fuel gas from the fuel tank to an engine body such that the fuel gas evaporated in the fuel tank is absorbed by oil in the engine body of the engine, characterised in that the engine is arranged below the fuel tank, and that the charge pipe passage includes: a first engine-side pipe passage part which is arranged above the engine body in a vertically extending manner on one side of the engine body in the vehicle widthwise direction; a second engine-side pipe passage part which is communicably connected to a lower end of the first engine-side pipe passage part on one side in the vehicle widthwise direction and extends from one side to the other side in the vehicle widthwise direction above the engine body; and a third engine-side pipe passage part which is connected to the second engine-side pipe passage part on the other side in the vehicle widthwise direction and is connected to the engine body, that a frame-side support part which supports the first engine-side pipe passage part is mounted on the vehicle body frame, an engine-side support part which supports the second engine-side pipe passage part is mounted on the engine, and at least a part of the charge pipe passage between the engine-side support part and the frame-side support part is formed of an elastic tube, and that in a plan view, the second engine side passage is arranged so as to pass below an intake device which extends rearwardly from an upper side surface of a cylinder head. a fuel tank which is arranged below a rider's seat and is supported on a vehicle body frame; a power unit which includes an engine generating power for driving a rear wheel, is swingably supported on the vehicle body frame; and a charge pipe passage which introduces a fuel gas from the fuel tank to an engine body such that the fuel gas evaporated in the fuel tank is absorbed by oil in the engine body of the engine, characterised in that the engine is arranged below the fuel tank, and that the charge pipe passage includes: a first engine-side pipe passage part which is arranged above the engine body in a vertically extending manner on one side of the engine body in the vehicle widthwise direction; a second engine-side pipe passage part which is communicably connected to a lower end of the first engine-side pipe passage part on one side in the vehicle widthwise direction and extends from one side to the other side in the vehicle widthwise direction above the engine body; and a third engine-side pipe passage part which is connected to the second engine-side pipe passage part on the other side in the vehicle widthwise direction and is connected to the engine body, that a frame-side support part which supports the first engine-side pipe passage part is mounted on the vehicle body frame, an engine-side support part which supports the second engine-side pipe passage part is mounted on the engine, and at least a part of the charge pipe passage between the engine-side support part and the frame-side support part is formed of an elastic tube, and that in a plan view, the second engine side passage is arranged so as to pass below an intake device which extends rearwardly from an upper side surface of a cylinder head.