This invention provides a method for forming an oxide layer on a metal substrate, which enables manufacture of an oxide layer with improved crystal orientation in comparison with that of the outermost layer of a metal substrate. The method for forming an oxide layer on a metal substrate 20 via RF magnetron sputtering comprises a step of subjecting the crystal-oriented metal substrate 20 exhibiting a c-axis orientation of 99% on its outermost layer to RF magnetron sputtering while adjusting the angle α formed by a perpendicular at a film formation position 20a on the metal substrate 20 and a line from the film formation position 20a to a point 10a at which the perpendicular magnetic flux density is zero on the target 10 located at the position nearest to the film formation position 20a to 15 degrees or less.