The object is to provide a process for dyeing that can provide an excellent dyeing effect while utilizing an oxidase, and a dyeing agent for use in the process. Provided is a dyeing agent comprising a modified enzyme obtained by adding positive charge by a chemical modification with an amine to an enzyme selected from the group consisting of an enzyme specified as EC 1.10.3.1, an enzyme specified as EC 1.10.3.2, an enzyme specified as EC 1.3.3.5, an enzyme specified as EC 1.10.3.4, an enzyme specified as EC 1.10.3.3 and an enzyme specified as EC 1.14.18.1. A process for dyeing using the dyeing agent is also provided.