The nurses were stabbed in the chest and abdomen but their wounds were not life threatening, police said, adding that a policeman was also wounded in his left arm.
Police arrested a 45-year-old male patient who had stabbed one nurse and ran way. The two other nurses and policeman were wounded as they tried to apprehend the man, police said.
Violent crime is rare in Japan where most incidents involve knives or swords due to the country's strict gun laws.In May, a knife-wielding man slashed at a group of schoolgirls at a bus stop, killing one girl and wounding 16 others in an incident that shocked the nation.