The sensor inserting device (10) includes a device body (18), a movement mechanism (20) which inserts a detector (14) and an insertion needle (32) into a body of a patient by moving a sensor (12) with the insertion needle (32), and a dwelling member (24) which is arranged on a moving path of the sensor (12) and attached to the sensor (12) by movement of the sensor (12) caused by the movement mechanism (20). The dwelling member (24) is allowed to dwell on the skin of the patient with the sensor (12) and the transmitter (16) connected at a location in which the detector (14) is inserted into the body of the patient.