Magnetization effects on the Young’s modulus of a magnetic elastomer consisting of polyurethane and barium ferrite have been investigated. The Young’s modulus was measured before and after magnetization at 1 T by dynamic viscoelastic measurements with a compressional strain. Giant reductions in storage modulus of ~10⁵ Pa was observed for the elastomer below volume fractions of 0.11. Oppositely, the magnetic elastomer with a volume fraction of 0.14 exhibited an increase in the storage modulus of ~10⁴ Pa after magnetization. Nonlinear viscoelastic responses, loss tangent, and particle dispersibility for the magnetic elastomer are discussed. Buy this Article