Magnetorheological elastomer (MRE) is a smart material where its stiffness vary with presence of magnetic field.These special properties lead to various application as mechanical devise such as damper. Damping coefficient is criteria that need to consider while designing the device. This paper aims to study the effect of iron filling and elastomer composition on a damping coefficient of MRE. Five MRE specimens with different CIP composition from 30 to 70% was prepared.the speciment was tested with testbed which is has a Constance distance permanent magnet(5mm) and motor speed (131.9Hz). The vibration amplitude in frequency domain was used to calculate the damping coefficient by half-power bandwidth equation. Experimental result indicates that the highest damping coefficient is at 30% CIP concentration and the lowest is at 70% CIP composition. As a conclusion, the damping coeficiet is decrease with increasing in CIP composition.this finding useful to design an optimal active damper for mechanical component.