In this paper, we proposed a structure of an active catheter using polypyrrole (PPy). PPy is one of conducting polymer actuators that are suitable for microactuator for medical use. We fabricated an active catheter of two actuator type which was coated with an electrolyte gel. It was driven in air, and a radius of curvature of 146mm was obtained. In order to enlarge the bending displacement of the catheter, we used thin metal films as electrode for polymerization of PPy. A trimorph actuator with an Au electrode and an electrolyte gel to drive PPy in air, exhibited 6.4 times larger curvature than that using a conducting polymer as electrode. We simulated the operation of the active catheter with the Au electrode to optimize various sizes by a finite element analysis.