Disclosed is a process for producing an amide or lactam in a high yield in a simple manner by allowing a rearrangement reaction of an oxime compound to proceed without causing large amounts of by-products such as ammonium sulfate.Specifically, disclosed is a process for producing an amide or lactam in which a corresponding amide or lactam is produced by rearranging an oxime compound in the presence of a compound containing a structure represented by following Formula (1): —Z—X   (1) wherein Z represents P, N, S, B, or Si atom; and X represents a leaving group, where Z is bonded to one or more atoms or groups besides X. In the process, X may be a halogen atom.