FLUID BRAKE DEVICE, AND VALVE TIMING ADJUSTMENT DEVICE

PROBLEM TO BE SOLVED: To provide a fluid brake device preventing change of a brake characteristic due to leakage and alteration of a magnetic viscous fluid.SOLUTION: A brake rotating body 130 includes a brake shaft 131 penetrating the inside and outside of a housing 110, and comes into contact with a magnetic viscous fluid 140 of a fluid chamber 114, whereby brake torque in accordance with viscosity of the fluid 140 is input therein. A magnetic seal sleeve 170 arranged in a form surrounding the brake shaft 131 along a rotating direction Dr in the housing 110 for forming seal gaps 180, 181 communicating with the fluid chamber 114 between the brake shaft 131 and itself is provided with magnetic flux guides 174, 175 for guiding magnetic flux to the brake shaft 131 through the seal gaps 180, 181 formed with the inner periphery-side brake shaft 131, and axial lengths Lsl_o, Lsl_i of inner peripheral surfaces 174a, 175a of the magnetic flux guides 174, 175 change in the rotating direction Dr of the brake shaft 131.