To provide a method of manufacturing concrete caisson on water and its equipment which allow to manufacture large caissons on water surface with simple equipment and to manufacture an object with a structure which can easily manufacture a bottom plate and a foundation on the water floor integrally when installing the bottom plate.

A form 5 for the caisson is installed on water by being supported by a floating body 1 floating on the water. A hanger 9 for supporting the caisson is embedded in the form 5 and concrete is placed. The caisson which is manufactured while the hanger 9 for supporting the caisson is supported by the floating body 1 is hung. The form 5 is moved relatively toward the upper part of the caisson by letting out the hanger 9 for supporting the caisson and lowering the caisson into the water after waiting for hardening of the concrete. The next concrete is placed as a joint one after another.