In a lawn mower for mowing lawns on a ground having a drive shaft adapted to transmit a rotational driving force of a operating motor (prime mover), three blades and a connecting member having a blade disk adapted to connect the blades with the drive shaft, a fan is integrally formed at the connecting member. The blades are attached to the connecting member at a circumference of the connecting member and to be movable relative to the connecting member in a radial direction of the connecting member.