Abstract: After treatment of the living pine wood nematodes, detailed observation was made on sections of all parts of the nematode with TEM, but no bacteria were found within the nematode body. However, many bacteria were found on the serface of the nematode body with SEM by using the method to treat SEM sample with less dehydrating steps. Those bacteria were morphologically similar, 1.48～1.73?μm long, diameter 0.49～0.62?μm. This is the first report on the site of pine wood nematode where bacteria are carried.