Provided is a coil assembly having improved heat resistance for use in a control rod driver, in which the heat resistance of coils is improved to increase the lifespan thereof and the deterioration of the coils and the fall of a control rod are thus securely prevented from occurring due to continuous operations of the control rod driver during an automatic load follow operation, thereby improving the safety and economic feasibility of a nuclear power plant, and a method for manufacturing the same. The coil assembly includes a covered wire (110) which includes a coil wire (111) and a polyether ether ketone (PEEK) coating layer (112) covering an outer circumferential surface of the coil wire (111) and is wound in multiple layers; a coil coating layer (130) formed by filling gaps in the covered wire (110) with varnish; an insulating tape layer (120) covering external sides of a wound layer of the covered wire (110) insulated by the coil coating layer (130); and silicon molding (140) covering external sides of the insulating tape layer (120).