Abstract: A catheter type sensor, which is inserted into a living body in order to directly measure within the living body biological data such as blood pressure, has at least one base in its distal end or intermediate portion, at least one sensor element supported on the base to detect biological data, and lead wires for electrically connecting together the sensor element and an external measuring device. The base, the sensor element and the lead wires are buried in a resin material which has excellent compatibility with living bodies and which is shaped in the form of a catheter. Accordingly, the whole of the cross-sectional area of the sensor can be utilized as a space for mounting the assembly constituted by the base, the sensor element and the lead wires.