A magneto-rheological elastomer composition (10) includes a matrix resin (12) and a magnetic powder (11). The magnetic powder (11) is contained in an amount of 30 to 70% by volume based on 100% by volume of the composition. The magneto-rheological elastomer composition (10) has an Asker C hardness of 5 to 60 as determined by the Standard SRIS0101 of the Society of Rubber Science and Technology, Japan. The average particle size of the magnetic powder is preferably 2 to 500 μm, and the matrix resin is preferably an organopolysiloxane. The storage modulus of the magneto-rheological elastomer composition preferably changes by five times or more upon application of a magnetic force with a magnetic flux density of 200 mT. Thus, the present invention provides a magneto-rheological elastomer composition that greatly changes its storage modulus upon application of magnetism, a method for producing the same, and a vibration absorbing device including the same.