Biology of Tabans amaenus Walker was studied, and following results were obtained: 1. The peaks of the emergence day were on July 20 for the male and July 29 for the female when the field collected larvae had been reared in the laboratory. 2. The most preferred plants, on which the eggs were laid, were graminous plants, specially Oryza sativa, Echipechlora crus-gall, Agropyon koryoense, and the most of the eggs were collected in the rice fields. 3. Greater portion of the egg masses were found at the height of 20-35cm of the plants, and the average numbers of the eggs per egg mass were 467.3${pm}$3.3. 4. The incubation period of the eggs was different with the temperature and found 7.5 days in June, 6.4 days in July, and 5.4 days in August. 5. The hatchability was 42.6-49.0% and 17.6-30.4% of the eggs were Parasitized by eggs Parasites. 6. The pupal periods were 24.1 days for the females and 19.4 days for the males, when field collected old larvae had been reared in the laboratory. 7. The habitats of verious developmental stages in relation to the distance from the hill were studied, and it was found 56.3% of the egg masses within loom, 62.8% of the larvae within 200m, and 64.2% of the adults emerged further than 250m from the foodhill. This may mean that activity of the emerged adults confined on the hill and the hatched larvae move down to the paddy field to seek for the optimum moisture as well as for the food.