A pipe joint for a radiator includes a connector portion, a pipe portion, a radiator hose fitting portion, and a radiator cap. The connector portion is connected to a coolant water introducing pipe of the radiator. The pipe portion extends upward from the connector portion. The radiator hose fitting portion extends from the pipe portion. The radiator hose fitting portion is connected to a radiator hose for returning coolant water from an internal combustion engine to the radiator. The radiator cap is mounted on an upper portion of the pipe portion.