A buoyant force control apparatus for scuba diving is used being installed on a diver's suit. Air supply to an air chamber formed within the suit is done, by pushing operations of opening and closing the air supply valve, from an air tank. Alternately, the driver holds the air breathe-in port or mouth piece between teeth while pushing a valve shaft slidably installed in an air supply valve. Air exhaustion from the air chamber is carried out by pulling one of pull strings attached to the first and second exhaust valves, respectively secured to both half portions of the front part of the diver's suit at different levels so as to separate them from each other.