The developmental and growth stages of the cattle tick, Haemaphysalis longicornis, reared on the rabbit under laboratory conditions and the life history were examined as a part of our ecological study. 1. The whole period of the developmental and growth stages consisting of the egg, larval, nymphal and adult stage was 2 to 3.7 months in the laboratory (27.9℃ on an average). 2. The female adult ticks which were fed on the rabbit after having been captured from cattle engorged and then dropped on a cage floor within average 6.2 (range 5-8) days, when the body weight averaged 213 (142-294) mg. But, the male adult ticks gained their weight only a little after feeding on the rabbit. 3. The pre-oviposition and oviposition periods averaged 5.4 (4-7) days and 18.9 (12-26) days, respectively, and the average of the total number of the deposited eggs was 2,552 (1,736-2,970). There was a positive correlation between the body weight of the engorged female and the total number of the deposited eggs. The average number of the deposited eggs per 1mg of the body weight was12.5. 4. The average weight of the newly deposited eggs was 0.05 mg and the average period of the egg stage was 20.1 (16-25) days. 5. The average weight of the unfed larvae was 0.03 mg, and the average period required for engorgement was 4.5 (3-6) days, by which time the mean body weight of the engorged larvae increased about 10 times (0.32 mg). 6. The average weight of the unfed nymphs was 0.24 mg, the average period required for engorgement was 4.3 (3-6) days and the mean body weight of the engorged nymphs increased about 12 times (2.88 mg) of the unfed ones. 7. The body weights of the unfed females and males just after moulting averaged 1.21 mg and 0.90 mg, respectively.