Softmaterials containing magnetic particles demonstrate the change in rheological properties upon magnetic field, this is called the magnetorheology. A variety of magnetorheological materials has been investigated for the past decade. The magnetic effect on the rheological properties strongly depends on not only the types of matrix but also magnetic particles. A magnetic gel consisting of polysaccharide matrix demonstrates negative and remarkable changes in dynamic modulus upon magnetization (~107 Pa). In this review, we survey the general magnetorheological effect of various softmaterials and describe the phenomenon and mechanism of the negative magnetorheological effect seen in the polysaccharide magnetic gels.