To elucidate pressure pain threshold of pericranial muscle due to involuntary, the effect of 30 min of forward head position(FHP) was studied in 20 patients with episodic tension-type headache and in 20 control without headache. Pressure pain thresholds were recorded before and after the FHP, and evaluated by pressure algometry. Thresholds increased in the patients and control after FHP. Relation between thresholds in patients and control before FHP were not significant differences, but thresholds increased in patients after FHP. So, involutary muscle contraction due to FHP may be effect pressure pain threshold of pericranial muscle.