YBa2Co3Oy prepared at 1200 K under reduced pressure forms a cubic perovskite type oxide with a superstructure (a = 1.24 [nm] : E phase). Heat treatments of the E phase oxide in oxygen of 0.106 [MPa] at 1100 [K], 1200 [K], and 1320 [K] formed a tetragonal oxide (a = 1.22 [nm], c = 1.25 [nm] : C phase), an orthorombic oxide (a = 0.389 [nm], b = 0.365 [nm], c = 1.253 [nm] : D phase), and a tetragonal oxide (a = 0.39 [nm], c = 1.13 [nm] : A' phase) with a small amount of other oxides, respectively. The magnetic susceptibilities of the E and C phases oxides are expressed as a sum of a temperature-independent term and the Curie-Weiss term. The D phase oxide is a ferromagnet with magnetization σ = 0.63 μB/Co and Curie temperature Tc = 57 [K]. The A' phase oxide is a paramagnet with anomalous susceptibility maximum at 170 [K]. The electrical resistances of the four oxide phases are semiconductive and, in addition, only the E phase oxide shows a remarkable resistance decrease below 200 [K].