Abstract: An underwater motive device includes a rear main housing including two opposite handle bar elements on two sides respectively, and longitudinal rear joining projections on an inner surface; a power mechanism in the rear main housing; a propeller driven by a driving shaft of the power mechanism; a bridging housing including a battery compartment, a forward joining member, a shoulder abutted the forward joining member, and a rear joining member; a hollow intermediate housing including two opposite handle bar members on two sides respectively, the handle bar members joined the handle bar elements, longitudinal front joining projections on an inner surface, and an internal annular limit element at a front end; and a front cone including a rear opening and a structure on an inner surface for securing to the forward joining member of the bridging housing.