Abstract: The present invention relates to a gas balloon with floating height control ability, more particularly, a gas balloon 1 capable of floating in air by static buoyancy of gas, comprising balloon member 2 and weight control member 4 of the balloon; wherein the balloon member 2 comprises reinforcement coating layer 6, silver coating layer 7 and outer surface fabric cloth 8 while said handle part 2a has magnetic plate 3 therein to control the weight of the balloon 1, having large and small piece 5, 5a. The gas balloon 1 according to the invention can keep its floating height to a constant level by removing said large and small piece 5, 5a continuously to lead rising of the balloon 1, especially, even in case the balloon 1 which is used for long term gradually falls down since it causes gas filled in the balloon member 2 flowing out of the member as time goes by, thus, induces loss of the static buoyancy of the member 2.