To establish the rapid detection method of airborne bacterial spores, we examined Bacillus anthracis spores by real-time PCR. One hundred liters of air were trapped on a filter of an air monitor device. After it was suspended in PBS, spores of B. anthracis were artificially added. The suspension was also heated at 95 degrees C for 15 min and used for real-time PCR using anthrax-specific primers. A single cell of B. anthracis was detected by real-time PCR within 1 h. Our results provide evidence that anthrax spores from the atmosphere can be detected rapidly, suggesting that real-time PCR provides a flexible and powerful tool to prevent epidemics.