A dish washing machine comprising: a tub defining a washing space therein; a steam generator generating steam during a washing operation; a water supply conduit connected to the steam generator supplying water to the steam generator; a steam flow conduit connected to the steam generator to guide steam generated by the steam generator into the washing space; characterized in that the dish washer comprises: an over-pressure prevention conduit having a first end and a second end, the first end connected to the water supply conduit and the second end connected to the steam flow conduit, and a first connection part having a first port, a second port and a third port, the first port connected to the water supply conduit, the second port connected to the steam generator, and the third port connected to the first end of the over-pressure prevention conduit; wherein the first connection part includes: a main conduit, wherein the first and second ports are located at opposite ends of the main conduit; and a sub-conduit, wherein a first end of the sub-conduit is connected to the main conduit and the third port is located at the opposite end of the sub-conduit, and wherein the sub-conduit diverges upward from the main conduit at a predefined angle with respect to the main conduit. a tub defining a washing space therein; a steam generator generating steam during a washing operation; a water supply conduit connected to the steam generator supplying water to the steam generator; a steam flow conduit connected to the steam generator to guide steam generated by the steam generator into the washing space; characterized in that the dish washer comprises: an over-pressure prevention conduit having a first end and a second end, the first end connected to the water supply conduit and the second end connected to the steam flow conduit, and a first connection part having a first port, a second port and a third port, the first port connected to the water supply conduit, the second port connected to the steam generator, and the third port connected to the first end of the over-pressure prevention conduit; wherein the first connection part includes: a main conduit, wherein the first and second ports are located at opposite ends of the main conduit; and a sub-conduit, wherein a first end of the sub-conduit is connected to the main conduit and the third port is located at the opposite end of the sub-conduit, and wherein the sub-conduit diverges upward from the main conduit at a predefined angle with respect to the main conduit. an over-pressure prevention conduit having a first end and a second end, the first end connected to the water supply conduit and the second end connected to the steam flow conduit, and a first connection part having a first port, a second port and a third port, the first port connected to the water supply conduit, the second port connected to the steam generator, and the third port connected to the first end of the over-pressure prevention conduit; wherein the first connection part includes: a main conduit, wherein the first and second ports are located at opposite ends of the main conduit; and a sub-conduit, wherein a first end of the sub-conduit is connected to the main conduit and the third port is located at the opposite end of the sub-conduit, and wherein the sub-conduit diverges upward from the main conduit at a predefined angle with respect to the main conduit. a main conduit, wherein the first and second ports are located at opposite ends of the main conduit; and a sub-conduit, wherein a first end of the sub-conduit is connected to the main conduit and the third port is located at the opposite end of the sub-conduit, and wherein the sub-conduit diverges upward from the main conduit at a predefined angle with respect to the main conduit.