PURPOSE: To provide an inexpensive brake having a short size in its radial direction.

CONSTITUTION: A brake device comprises a first member 2 on the surface of which a viscous fluid 6 or a pasty material made of a viscous fluid applied, a second member 1 making relative movement to the first member 2, a contact member 3 fixed to the second member 1, and brought in contact with the other member, and a spacer 4 for changing the contact amount of the contact member 3 according to the relative movement to the second member 1.