Life history of hard ticks, Haemaphysalis longicornis and H. megaspinosa, was studied in Boso Peninsula on central Japan from February 2002 to January 2003. Engorged individuals were also reared under the controlled laboratory conditions. In both species, larvae appeared on plants in July and disappeared by June. Nymphs in litter and soil increased in the numbers from September. Nymphs of H. megaspinosa were found in litter and soil from May to September although they were active on plants from November to April. Developmental diapause was also observed for engorged nymphs and engorged females of H. megaspinosa under the laboratory conditions.