Provided are surface treatment agents that enable surfaces with a chemically fixed lubricant to be produced instead of a resin coating which has drawbacks, such as that lubricity is reduced due to separation, peeling or the like of the coating during the movement within a vessel or tube； and medical devices, such as catheters, having a surface at least partially treated with such a surface treatment agent. The present invention relates to a surface treatment agent for medical devices which contains a copolymer of a hydrophilic functional group-containing monomer and an epoxy group-containing monomer.
