Clean room purification system

A clean room purification system that can ensure a high ceiling height and prevent ceiling materials from falling during an earthquake is proided. The clean room purification system (1) purifies the clean room (2) installed in the building. The clean room purification system (1) is equipped with an air conditioner (10); a porous diffusion membrane (20), which is installed inside the clean room (2); an air supply pipe (30), which is blown from an outlet (12) of the air conditioner (10) to reach the porous diffusion membrane (20); and a return air duct (40), which reaches a suction inlet (11) ofthe air conditioner (10) from the floor (3) of the clean room (2). The air conditioner (10) is provided with a box (13), a blower (14) arranged in the box (13), a coil (16) arranged in the box (13) and used for adjusting temperature and humidity, and an intermediate filter (15) and an HEPA filter (17) arranged in the body (13). The air conditioner is driven, and high-cleanliness air is supplied to the porous diffusion me