Brake squeal is an important issue that makes car drivers uncomfortable and has caused the automotive industry to significant annually warranty cost. The present work investigates the effect of the radial contact area between pad and disk on brake squeals in automotive disk brake. Experimental apparatus using in brake test is composed of actual brake unit with floating type caliper. The radial contact area between disk and pad is changed by using pad with inner circumference cut or outer circumference cut. Using inner and outer pad without cut, incident rate of squeal related to 2nd in-plane mode of disk is high. Squeal incident rate using both inner and outer pad with inner or outer circumference cut is more reduced than that using only inner pad with inner or outer circumference cut and outer pad without cut. Using inner and outer pad with inner circumference cut, though incident rate of squeal related to 2nd in-plane mode of disk is not reduced, some squeals are controlled. Using inner and outer pad with outer circumference cut, most of squeal is controlled. When the contact area between pad and disk is changed, we consider the effect of brake torque, pressure distribution between disk and pad, and accelerance of disk on squeal.