Use of an ink refill container configured to refill ink to an ink tank, wherein the ink tank includes: an ink storage chamber configured to store ink; a needle that extends in an upward direction and that includes a flow passage in communication with the ink storage chamber; an ink inlet in which the needle is arranged; and a receiving surface having the ink inlet, the receiving surface extending along a direction intersecting the needle extending direction; wherein the ink refill container comprising: a container main body including an ink container chamber configured to contain the ink; an ink outlet-forming portion that is provided on an end portion of the container main body, the ink outlet-forming portion having an ink outlet that allows the ink to flow out from the ink container chamber; and a valve provided in the ink outlet-forming portion, the valve configured to be opened by the needle inserted into the ink outlet; wherein the ink outlet-forming portion includes a positioning portion, the positioning portion provided at a position on an outer side of the ink outlet-forming portion, the positioning portion being closer to the container main body than the valve is to the container main body in a central axis direction of the ink outlet, when the needle is inserted into the ink outlet, the valve is opened and the positioning portion abuts against the receiving surface. wherein the ink tank includes: an ink storage chamber configured to store ink; a needle that extends in an upward direction and that includes a flow passage in communication with the ink storage chamber; an ink inlet in which the needle is arranged; and a receiving surface having the ink inlet, the receiving surface extending along a direction intersecting the needle extending direction; an ink storage chamber configured to store ink; a needle that extends in an upward direction and that includes a flow passage in communication with the ink storage chamber; an ink inlet in which the needle is arranged; and a receiving surface having the ink inlet, the receiving surface extending along a direction intersecting the needle extending direction; wherein the ink refill container comprising: a container main body including an ink container chamber configured to contain the ink; an ink outlet-forming portion that is provided on an end portion of the container main body, the ink outlet-forming portion having an ink outlet that allows the ink to flow out from the ink container chamber; and a valve provided in the ink outlet-forming portion, the valve configured to be opened by the needle inserted into the ink outlet; wherein the ink outlet-forming portion includes a positioning portion, the positioning portion provided at a position on an outer side of the ink outlet-forming portion, the positioning portion being closer to the container main body than the valve is to the container main body in a central axis direction of the ink outlet, a container main body including an ink container chamber configured to contain the ink; an ink outlet-forming portion that is provided on an end portion of the container main body, the ink outlet-forming portion having an ink outlet that allows the ink to flow out from the ink container chamber; and a valve provided in the ink outlet-forming portion, the valve configured to be opened by the needle inserted into the ink outlet; wherein the ink outlet-forming portion includes a positioning portion, the positioning portion provided at a position on an outer side of the ink outlet-forming portion, the positioning portion being closer to the container main body than the valve is to the container main body in a central axis direction of the ink outlet, when the needle is inserted into the ink outlet, the valve is opened and the positioning portion abuts against the receiving surface.