Catheter-based endovascular cerebrovascular therapy is a less physically demanding treatment for patients. In this treatment, a catheter is used to deliver a therapeutic device to the diseased area. X-rays are used to capture images of the device and blood vessels. Therefore, this treatment has the problem of cumulative radiation exposure to the surgeon and staff. A teleoperated robot has been proposed as a solution to this problem. Because cerebral blood vessels are thin and easily torn, the teleoperated robot needs a sensor to measure the insertion force of the treatment device. We have been developing the sensor, the detection accuracy of which was 0.02N in our previous study. The proposed sensor has an improved internal structure and improved detection accuracy to 0.01N. In addition, the practicality of this sensor has been further improved. This paper describes the structure and features of this insertion force sensor, accuracy measurements, and experimental results using a blood vessel model.