A fitness module box including a box body having an entrance in a side. The box body includes a framework having a structure and a finishing plate structure finishing outer surfaces of the framework. In the framework top frames spaced apart from bottom frames are connected to the bottom frames using side frames. The fitness module box is provided as a modular structure, such that two or more such fitness module boxes can be connected together, allowing the scale of a fitness facility to be adjusted in consideration of the number of users. An operator may have a significant advantage in terms of the operation of the fitness facility. A user may make a reservation for one of a variety of fitness module boxes at a desirable place and time, and may pay a fee based on the time of use.