The mixed surveying method of precise mapping by total station-pen computer system and soft sediments sampling system (percussion drilling set; engine type) was applied to the fault displaying major flexural deformation for the purpose of evaluation of fault activity. As results, we clarified that the Asahi fault of the Tokachi Fault Zone, Hokkaido, Japan, has lastly activated ca.200 ka with the single vertical slip of about 1.5 m, and its time recurrence is about 7,000 years, although the activity has diminished since several ten thousands years ago.