The relationship between magnetic-field sensitivity and the volume fraction of magnetic particles for magnetic elastomers was investigated. The magnetic-field dependence of the storage modulus for magnetic elastomers was measured by dynamic viscoelastic measurements under magnetic fields with a constant sweep rate of 3.7 mT s(-1). The magnetic-field sensitivity was determined by the initial slope of the storage modulus using an exponential function. It was revealed that the maximum magnetic-field sensitivity was 1.8 x 10(-2) mT(-1) at the maximum volume fraction of magnetic particles.