Effects of applying chitosan [poly-(1→4)-β-D-glucosamine] and water soluble inorganic fertilizer to soils on seedling growth of Eustoma grandiflorum (Raf.) Shinn. cv. Kairyou Wakamurasaki were investigated. The treatment of 1.0% chitosan soil mixture (w/w), combined with a fertilizer containing the same amount of nitrogen as in 1.0% chitosan, significantly promoted plant growth, compared to the treatments of 1.0% chitosan soil mixture and of fertilizer with equal or double amounts of inorganic nitrogen contained in the 1.0% chitosan, when measured 7 weeks after sowing. Nitrogen and phosphorus concentrations in the shoot and root in the fertilizer or chitosan combined treatment were higher than those in the untreated control. Chitosan supplementation into in vitro culture of seedlings also promoted plant growth regardless of chitosan concentration, compared with chitosan-free, half or full strength of Murashige-Skoog medium.