A sensor includes an inflow section into which an analyte liquid flows; a first cover member; a detection element including an element substrate located on an upper surface of the first cover member, and a detection section which is located on an upper surface of the element substrate and is configured to detect a target contained in an analyte liquid; an intermediate cover member including a first upstream portion; a second cover member including a second upstream portion; and a flow channel which is surrounded by the intermediate cover member and the second cover member, is continuous with the inflow section, and extends at least to the detection section. A contact angle θ2a of a lower surface of the second upstream portion of the second cover member with the analyte liquid is smaller than a contact angle θ3 of an upper surface of the detection element with the analyte liquid.