Abstract: For the solution growth, a solvent is used which is composed of a mixture of an oxide containing at least one member of those elements which constitute the oxide crystal and a halide containing at least one member of those elements which constitute the oxide crystal. The process enables the temperature of crystal growth to be lowered to a significant extent, avoids inclusions such as impure anionic elements from getting intruded into the oxide crystal, while retaining adequate crystal growth through solution growth, and affords, in spite of an atmospheric mode of crystal growth and with the pinning force of magnetic flux used to advantage, the same level of beneficial effects as in a mode of crystal growth at a low oxygen pressure.