Rotor for eddy current deceleration device

A cylindrical part of a rotor for an eddy current deceleration device of the present embodiment has a chemical composition consisting of, by mass %, C: 0.05 to 0.15%, Si: 0.10 to 0.40%, Mn: 0.50 to 1.00%, P: 0.030% or less, S: 0.030% or less, Mo: 0.20 to 1.00%, Nb: 0.020 to 0.060%, V: 0.040 to 0.080%, sol. Al: 0.030 to 0.100%, B: 0.0005 to 0.0050%, N: 0.003 to 0.010%, Cu: 0 to 0.20%, Ni: 0 to 0.20%, Cr: 0 to 0.10%, and the balance: Fe and impurities, and in which the total area fraction of martensite and bainite in a microstructure is more than 95.0%, and the number density of carbides having an equivalent circular diameter of 100 to 500 nm is 0.35 to 0.75 particles/μm2.