Armrest and seat with armrest

An armrest comprising:

• an arm-side wire harness including an electric wire and an arm-side connector that is on an end of the electric wire and is to be coupled to a mount member-side connector mounted on a mount member;
• and
• an arm body member including an arrangement section in which the electric wire of the arm-side wire harness is arranged and a mount member-side wall that is to be arranged opposite the mount member, wherein the arm body member is configured to be fixed to the mount member while the mount member-side wall is opposite the mount member, wherein
• the mount member-side wall includes a connector insertion hole through which the mount member-side connector is configured to be inserted,
• the arm-side connector and the mount member-side connector are configured to be arranged in the arrangement section,
• the arm body member includes an operation hole that is continuous from the arrangement section, and
• the operation hole opens toward an opposite side from the mount member.