MR head and double-layered medium used for perpendicular magnetic recording interact strongly each other. In order to investigate the influences of the interaction on MR head read characteristics, we perform micromagnetic simulations considering the interaction between head and medium. The output of shielded MR head are larger than those of non-shielded MR head due to reducing the demagnetization field in the free layer. However, the interaction between shield and soft under layer causes decrease in the signal output and the widening of reproduced wave form, which might result in degradation of resolution.