The photocatalyst equipment consists of a titanium dioxide (TiO2) membrane and an ultraviolet (UV) lamp. The authors studied lf the photocatalyst equipment was practically useful in sterilizing environmental microorganisms in the health care facility. The number of microorganisms (CFU, colony forming unit) was compared in the cases of no sterilization (control), UV irradiation alone and photocatalyst sterilization. As a result, a statistical difference was observed between control and the photocatalyst sterilization against airborne microorganisms (p<0.01) but not against surface microorganisms (p>0.2). The photocatalyst uses an air sucking system，so it may be ineffective against microorganisms tightly attached to surfaces (adhesive microorganisms). However, the effectiveness and significant difference compared with control of the photocatalyst to sterilize airborne microorganisms in the health care facility was successfully confirmed.