A modular cooling tower that serves to cool down cooling water or condense coolant. The modular cooling tower has a greatly reduced height, is easily transported and installed as a finished product, prevents damage and has an improved aesthetic appearance because components are installed inside a casing, efficiently circulates cooling water and air into a heat exchanger unit without a bypass flow, ensures excellent heat exchange performance by preventing the recirculation of exhaust air, makes it easy to inspect and repair components inside the modular cooling tower, is easily installed in a multi-stage structure on the roof of a building, makes the upper space of the modular cooling tower to be used, and makes it easy to install a cover wall and covering members that cover the modular cooling tower.