To move a droplet along the surface of a moving surface formation member by a simple technique.
Magnetic field formation members 4A, 4B which form magnetic field inclinations that a magnetic field becomes small as the droplet on the surface of a moving surface formation member 1 is separated along the surface from an area where the droplet is located on the surface of the moving surface formation member 1 are provided on both surfaces of the moving surface formation member 1 consisting of a nonmagnetic material for forming a moving surface of the droplet, respectively. Then, the droplet is moved along the magnetic field inclinations by relatively moving the moving surface formation member 1 and the magnetic field formation members 4A, 4B along the surface.