A sensor insertion device for inserting a detection element of a sensor configured to measure biological information of a subject into the body of the subject includes a device body a data process unit attached to the device body, a movement mechanism detachably attached to the device body, the movement mechanism being configured to move the detection element together with an insertion needle configured to be stuck into the body of the subject to insert the detection element and the insertion needle into the body of the subject and a displacement preventing member.
