The in-situ measurement of fluence dependence of electrical resistivity at 100K has been performed for EuBa2Cu3Oy irradiated at 100K with various energetic ions (Cl, Ni, Br, and I) at energy of 90–200MeV. Decreasing slope of resistivity-fluence curves has been observed for irradiations with 120MeV Cl, 90MeV Ni, and 185MeV Ni, while increasing slope of the curves has been observed for irradiations with 120MeV Br, 125MeV Br, and 200MeV I. It is assumed that the damaged region has a cylindrical shape along ion path and a higher resistivity than the undamaged matrix region. The calculated resistivity-fluence curve fitted well with the experimental data when using the diameter and the resistivity of the damaged region as fitting parameters. The obtained diameter and the resistivity of the damaged region have increased with increasing the electronic stopping power, Se. Successive annealing of the specimens up to 300K after irradiation has resulted in 50–70% recovery of irradiation-induced resistivity change at 100K. The diameter of the damaged region has been larger than that of amorphous tracks observed by transmission electron microscope. This result is discussed in relation to the result of annealing experiment.