A container apparatus for an object to be dropped, which contains an object to be dropped functioning as a point marker or a hydrographic conditions measuring device or the like and is dropped by a transport airplane such as an aircraft flying in the air to a water surface of sea, lake or the like, or to land or the like. The container apparatus follows a substantially uniform trajectory after being dropped by the transport airplane, and after being dropped, reduces the flight speed thereof to a fixed speed, to release the object to be dropped housed therein.