Due to economic growth, human beings have been coming in greater contact with various chemicals. Thus, the people who have become the chemical sensitive are also increasing, which results in anaphylaxis for various chemicals. Recently, a sick house syndrome is occurring frequently in an indoor environment. Especially, since the aged and infants who are physically weak, pass their time mainly in a room, there is a high risk for them to fall into the syndrome, of which the results are asthma or allergy. In this study, the ability of houseplant (Golden pothos) to remove the chemicals was examined. An indication of the ability, purification rate P_a of the plants, was examined in an experimental sealed chamber. P_a was derived from the measurements by tin oxide gas-sensor characteristics for a chemical. To calculate P_a, the peak of the sensor output was divided by the full-width at half maximum. The following chemicals were examined; formaldehyde, toluene, xylene, benzene and trichloroethylene. The rate became high when the plant was illuminated. The smaller the molecular weight of a pollutant was, the larger the purification rate became. Namely, it took a long time to remedy an indoor environment when chemicals with large molecularweight were adopted in the architecture-materials. Gaseous chemicals diffuse directly into soil. Features of the sensor characteristics in the soil were similar to the characteristics in the chamber atmosphere. Low purification ability of potted soil without plants was found. In this study, it was demonstrated that the plant tested had a higher ability to absorb ammonia than formaldehyde.