PURPOSE: To reduce friction which is generated between two solid contact surfaces regardless of contact surface direction and the interatomic distance of two solid.

CONSTITUTION: In two crystal bodies A, B, both clean surfaces are brought in contact with each other. A supersonic oscillator 10 is provided on the contact surface of the crystal body A and the surface of an opposite side. Lattice vibration of atom of the crystal body A is stimulated by supersonic which is oscillated from the supersonic oscillator 10. Since atom on the contact surface of the crystal body A gets over the fence of potential energy which is formed from the atom arrangement of the contact surface of the crystal body B by energy of the lattice vibration, two crystal bodies A, B are relatively performed translation even if there is no outer force applied on the crystal body A.