Magnetic properties of glassy oxide films which exhibit ferromagnetism and ferroelectricity simultaneously above room temperature prepared by reactive rf sputtering are presented. Nominal film composition is the solid solution compound system expressed by (1-x)BiFeO3‐x ABO3, x=0–1 where ABO3 denotes ferro‐ (antiferro‐) electric perovskites, such as BaTiO3, PbTiO3, and PbZrO3. Spontaneous magnetization 4πMs for as‐deposited films is small behaving paramagnetically and does not show the compositional dependence. After annealing at temperatures of 600–700 °C in either air or PbO atmosphere, considerably large 4πMs exceeding 1 kG appears at the solid solution composition. All samples with large 4πMs are x‐ray amorphous and a rapid decrease in 4πMs takes place after annealing at higher temperatures (≳800 °C), where still unidentified crystallites are precipitated. Mössbauer absorption spectra were done to understand the origin of ferromagnetism. Besides pronounced magnetic (and/or dielectric) properties, these films have a high transmittance from visible through near‐infrared regions, so that they are expected to be useful as optoelectronic device materials.