Terao's factorization theorem shows that if an arrangement is free, then its characteristic polynomial factors into the product of linear polynomials over the integer ring. This is not a necessary condition, for example, many integer-rooted non-free arrangements have been found in [9]. However, still main examples whose characteristic polynomials factor over the integer ring are free arrangements. On the other hand, the localization of a free arrangement is free, and its restriction is in many cases free, thus its characteristic polynomial factors. In this paper, we consider how their integer, or real roots behave.