To effectively engage an engine brake.

An automatic centrifugal clutch device for a vehicle comprises a clutch element 25 on the prime mover side driven by an engine; a clutch element 18 on the driven side linked to the drive wheel side; a frictional member 43 on the prime mover side rotatably integrally formed at a clutch element 25 on the prime mover side; a frictional member 45 on the driven side rotationally integrally arranged at the clutch element 18 on the driven side; a centrifugal movement member 53 moved from the centripetal position 53a side to a centrifugal position 53b side through a centrifugal force along with the increase of the number of revolutions of an engine to bring the frictional member 43 on the prime mover side and the frictional member 45 on the driven side into pressure contact with each other and into a clutch engagement state; and a connection holding mechanism 61 to hold the centrifugal movement member 53 at the vicinity of the centrifugal position 53b when rotation of the clutch element 18 on the driven side procedes rotation of the clutch element 25 on the primer mover side with the centrifugal member 53 situated on the centrifugal position 53b side.