We report the suppression of the critical temperature Tc in single crystalline Ba(Fe1−xCox)2As2 at under-, optimal-, and over-doping levels by 3MeV proton irradiation. Tc decreases and residual resistivity increases monotonically with increasing the dose. The low-temperature resistivity does not show the upturn in contrast with the α-particle irradiated NdFeAs(O,F), which suggests that proton irradiation introduces nonmagnetic scattering centers. Critical scattering rates for all samples obtained by three different ways are much higher than that expected in s±-pairing scenario based on inter-band scattering due to antiferro-magnetic spin fluctuations.