To realize a smooth connection in a two-joint type series connection device and prevent or reduce fatigue of a player caused by shock generated at a connection part between each connection member and a connection rod.

In a two joint type series connection device to connect two moving bodies together through the joints of two connection member 1, 3 arranged at both ends of a connection rod 2, the joints are composed of a rotation connection parts 1T and 2S, 2P and 3P, and the rotational axes HS, VS of both the joints are arranged so that they may not cross at right angles and not be in parallel. The relative change between two substances, e.g. a water- skiing means and a boat can be allowed by the cooperation of the degree of freedom around one axis HS and the degree of freedom around the other axis VS, and accordingly there is no need of play at the joint parts, which secure a smooth connection for reducing the fatigue and energy-consumption of a player caused by shock and the like at the joint parts.