Abstract: The invention relates to a pressure sensor implanted into the skull to emit an electrical signal representing the intra-cranial pressure; this sensor is of the type which includes on one hand a test body (1) comprising a deforming diaphragm (3) and of an undeforming guard ring (2), and on the other hand a deformation detector (5) associated with the diaphragm; the test body (1) is made of an integral piece, in particular plastic, and has a continuous front side (1a) which preferably is planar; the mechanical and dimensional properties of the constituent plastic are matched in such a manner that under the maximum pressure of 30 kilopascals, the diaphragm deflection is within a predetermined range; within this range, the dura mater pressed by the sensor transmits faithfully the intracranial pressure with adequate sensitivity to employ a resistive type transducer which simultaneously is simple, rugged compact and economical.