To manufacture an artificial crystal lower in linear defect density than that by a conventional method by suppressing defects present in a seed crystal from reflecting.

A buffer layer 102 comprising silicon dioxide having the crystallization degree different from that of quartz crystal is formed on the surface of a quartz crystal plate 101, and silicon oxide crystal is grown by a chemical vapor phase growth method using tetraethoxysilane gas, oxygen gas and hydrogen chloride gas on the buffer layer 102 to form a single crystal silicon oxide film 103. The quartz crystal plate 101 having the single crystal silicon oxide film 103 formed thereon is used as a seed crystal to grow artificial crystal on the single crystal silicon oxide film 103 by a publicly-known hydrothermal synthesis method to form artificial crystal 104.