A vehicle side door includes: a door main body; a mirror stay fixed to the door main body so as to be at least partially placed outwardly from the door main body, the mirror stay including a support portion placed outwardly from the door main body; and a mirror unit including a mirror holder supported by the support portion, and a mirror supported by the mirror holder, wherein: the door main body includes an outer panel constituting an outer face of the door main body, an inner panel placed inwardly from the outer panel and fixed to the outer panel, and a reinforcing member fixed to the inner panel or the outer panel; and the mirror stay is fixed to the reinforcing member.