A detection method for detecting the presence or amount of a detection target substance in a specimen, the method comprising: a step of supplying a liquid to a detection chip including a housing having an opening portion and internally housing a liquid and including an elastic sheet (50, 50', 50") covering the opening portion and having a penetrating portion (51, 51', 51") providing communicating between the inside and the outside of the housing, specifically by inserting a liquid delivery nozzle to the housing via the penetrating portion (51, 51', 51") and supplying the liquid into the housing in a state where the nozzle is in contact with the elastic sheet (50, 50', 50") so as to close the penetrating portion (51, 51', 51"), wherein the penetrating portion (51, 51', 51") is one of a hole and a notch, one of a maximum length of the opening of the hole and a maximum length of the notch is smaller than an outer diameter of the nozzle at a portion coming in contact with the elastic sheet (50, 50', 50") when the nozzle is inserted so as to close the penetrating portion (51, 51', 51") when the liquid is supplied into the housing, wherein the elastic sheet (50, 50', 50") is joined to a periphery of the opening portion via an adhesive sheet, and wherein the adhesive sheet includes a through hole (41, 42, 71) at a position corresponding to the penetrating portion (51, 51', 51"), and a minimum length of an opening of the through hole (41, 42, 71) is greater than the outer diameter of the nozzle at a position corresponding to the through hole (41, 42, 71) when the nozzle is inserted to the housing so as to close the penetrating portion (51, 51', 51") when the liquid is supplied into the housing. a step of supplying a liquid to a detection chip including a housing having an opening portion and internally housing a liquid and including an elastic sheet (50, 50', 50") covering the opening portion and having a penetrating portion (51, 51', 51") providing communicating between the inside and the outside of the housing, specifically by inserting a liquid delivery nozzle to the housing via the penetrating portion (51, 51', 51") and supplying the liquid into the housing in a state where the nozzle is in contact with the elastic sheet (50, 50', 50") so as to close the penetrating portion (51, 51', 51"), wherein the penetrating portion (51, 51', 51") is one of a hole and a notch, one of a maximum length of the opening of the hole and a maximum length of the notch is smaller than an outer diameter of the nozzle at a portion coming in contact with the elastic sheet (50, 50', 50") when the nozzle is inserted so as to close the penetrating portion (51, 51', 51") when the liquid is supplied into the housing, wherein the elastic sheet (50, 50', 50") is joined to a periphery of the opening portion via an adhesive sheet, and wherein the adhesive sheet includes a through hole (41, 42, 71) at a position corresponding to the penetrating portion (51, 51', 51"), and a minimum length of an opening of the through hole (41, 42, 71) is greater than the outer diameter of the nozzle at a position corresponding to the through hole (41, 42, 71) when the nozzle is inserted to the housing so as to close the penetrating portion (51, 51', 51") when the liquid is supplied into the housing.