Abstract: The present invention relates to a magnetorheological fluid and a manufacturing method thereof. The magnetorheological fluid according to the present invention includes: a dispersion medium; magnetic particles; and a thixotropic agent, in which the magnetorheological fluid has viscoelasticity, and when shear stress ? of the viscoelasticity of the magnetorheological fluid is ? = ?0sin(wt) and shear strain ? is ? = ?0sin(wt + ?) = G?sin(wt) + G?cos [G? is referred to storage modulus and G? is referred to as loss modulus], when a magnetic field is applied, the slope of G? is equal to or less than 0 for the range from 0.01% shear strain applied to the magnetorheological fluid to the shear strain value satisfying tan ? = G? / G?= 1.