PURPOSE: To obtain a float, employed on sea, lake and the like and excellent in strength and durability, and the manufacturing method of the same.

CONSTITUTION: A blow molded form F made of resin is filled with expandable resin grain by 60-80% of the internal volume of the blow molded form and, thereafter, foaming urethane stock solution is poured employing a probe P while rotating the molded form F. The manufactured float is filled with 60-80 volume % of expandable resin grain and 40-20 volume % of foaming urethane. The float, whose internal space of blow molded body is filled with a composite, in which expandable resin grain is dispersed uniformly into the foaming urethane, can be obtained without employing a device of large scale such as a press or the like. According to this method, the cost of the float is inexpensive, the strength of the same is high and durable. Further, even when the blow molded part is broken, the filled expandable resin grain will never be dispersed on the sea and the like.