A method involves supporting both a sensor which measures biological information and an insertion needle at a location proximally spaced from the distal end portion of a device body. The sensor includes a detector which detects a body fluid component of the patient used to measure the biological information, and a signal processor which is attached to the device body and which processes a signal including the biological information. The method also involves moving the sensor and the insertion needle in the distal direction so that the detector and a portion of the insertion needle protrude distally beyond the distal end portion of the device body, separating the insertion needle from the sensor by moving the insertion needle relative to the sensor toward a proximal direction, and electrically connecting the sensor and the signal processor by operation of the device body after the insertion needle is separated from the sensor.
