This research was performed to investigate the effect of formaldehyde removal and confirm the utility of plants as indoor environment improvement systems. The plant materials used in this study were Fatsia japonica, Ardisia japonica, Ardisia pusilla and Davallia mariesii. Plants were placed in an airtight chamber under artificial formaldehyde. The initial formaldehyde concentration in the chamber was $500{\pm}30ppb$, and the conditions of $1,500{\sim}2,000lux$ light, $25{\pm}5^{\circ}C$ temperature and $80{\sim}90%$ humidity were maintained. Each chamber was treated as no plant, plant-only and Plant+soil. The total leaf number for Davallia mariesii, Ardisia japonica, Ardisia pusilla, and Fatsia japonica was 40.8, 48.6, 62.3, and 11.8 respectively. The total leaf space n of those plant materials were $2,385cm^2,\;1,252cm^2,\;2,468cm^2\;and\;1,262cm^2$ respectively. The formaldehyde concentration was reduced to $80{\sim}90%$ of the initial concentration in plant-only and Plant+Soil treatment chamber of all species in 12 hours. In the plant-only chamber, Fatsia japonica had removed formaldehyde density by 95% after 12 hours while Ardisia japonica had removed 90%. In the case of Ardisia pusilla, the early removal rate was higher in the plant-only treatment chamber than the Plant+Soil treatment chamber. The formaldehyde removal rate of Davallia mariesii was 98% after 12 hours. In the Plant+Soil treatment chamber, the amount of removal of formaldehyde per time of Davallia mariesii, Ardisia japonica, Ardisia pusilla, and Fatsia japonica was 20.42ppb/hr, 16.28ppb/hr, 2.5.42ppb/hr, 10.28ppb/hr respectively. In the plant-only, That was 22.50ppb/hr, 20.97ppb/hr, 20.83ppb/hr, 20.97ppb/hr respectively.