Thermal asperity (TA) response of merged MR heads, due to the momentary contact between the heads and recording media, is simulated by the 3D finite element method. In this simulation, the thermal conduction and thermal distribution of an MR. head, and the TA responses superposed on the read-back signals are numerically simulated. The result are shown as follows: (a) the simulated TA response closely agrees with the experimental TA response; (b) the simulated TA response decreases drastically when a contact point is more than 5 μm away from the MR-element; and (c) the read gap material with high thermal conductivity is very effective on reducing TA responses.