In this study, we installed the odor sensors in patient room and clarified the variable factors affecting the level of odor. The level of odor changed when there were diaper changes, feeding tubes, patient repositioning, and cleanup, etc. And we compared the level of odor in the ordinary patient room with at the time of diaper change by odor measurement method by olfaction. There were some cases in which the odor concentration in the ordinary patient rooms and at the time of diaper changing were equivalent to 31. Patient rooms of the 32 year old building showed odor concentration as high as 230. However, about odor intensity, unpleasantness and acceptability, the level of odor of the diaper change patient room and the patient room of 32 year old building became high. It was suggested that the remaining odors were accumulated while repeatedly performing diaper changes with the door closed, therefore gradually raising the level of odor. The dilution ratio until threshold value of hydrogen sulfide and methyl mercaptane indicated about 20. These components are considered to influence sensory evaluation.