To clarify the effect of the climate warming on the soil heterotrophic microbial community in the warm temperate evergreen broad-leaved forest, we conducted a soil warming experiment in a secondary forest of Higashi-Hiroshima, western Japan. Ten trench plots (1m x 1 m) with root barriers for preventing root regrowth were established in the forest. The plots were divided into two treatments, warming and control. Soil of warming treatment was warmed by 3 °C using infrared heaters for three years. We used phospholipid fatty acid (PLFA) analysis to examine the soil heterotrophic microbial community composition. The total content of PLFAs (TotPLFAs) was used to indicate the total microbial biomass. The content of certain PLFAs, previously reported to be markers for bacteria and fungi, were used to indicate those biomass. There were no significant differences in TotPLFAs, bacterial PLFAs (BactPLFAs), and fungal PLFAs (FungPLFAs) contents between the warming treatment and control. However, the ratios of FungPLFAs contents to BactPLFAs contents were significantly lower in warming treatment than in the control. These results suggest that soil heterotrophic microbial community structure in the warm temperate evergreen broad-leaved forest is likely to change under climate warming.