A method for diagnosis of resistance to an anticancer agent and/or radiation of a subject with cancer, the method including: providing an isolated cancer tissue from a subject with cancer; culturing the cancer tissue into a cancer organoid in a 3D cell culture plate: treating the cultured cancer organoid with an anticancer agent and/or radiation; and selecting the cancer organoid treated with the anticancer agent and/or radiation as a cancer organoid having resistance to an anticancer agent and/or radiation when the cancer organoid treated with the anticancer agent and/or radiation has a viability equal to or more than that before the treatment with the anticancer agent and/or radiation, wherein in the culturing of the organoid, the 3D cell culture plate comprises 0 to 2 vol% of an extracellular matrix-based hydrogel, and wherein the 3D cell culture plate comprises: a well plate comprising a plurality of main wells and a plurality of sub wells formed at lower portions of the main wells to be injected with a cell culture solution and comprising recessed parts on a bottom surface thereof; and a connector for large-capacity and high-speed high content screening, which supports the well plate, and the connector for high content screening comprises a base equipped with a fixing means so as to be attached to and detached from a lower end of the well plate and a cover positioned on an upper portion of the well plate to be coupled to the base, the main well has a step formed so as to be tapered at a predetermined site, and the step has an inclination angle (θ) ranging from 10 to 60° with respect to a wall of the main well. providing an isolated cancer tissue from a subject with cancer; culturing the cancer tissue into a cancer organoid in a 3D cell culture plate: treating the cultured cancer organoid with an anticancer agent and/or radiation; and selecting the cancer organoid treated with the anticancer agent and/or radiation as a cancer organoid having resistance to an anticancer agent and/or radiation when the cancer organoid treated with the anticancer agent and/or radiation has a viability equal to or more than that before the treatment with the anticancer agent and/or radiation, wherein in the culturing of the organoid, the 3D cell culture plate comprises 0 to 2 vol% of an extracellular matrix-based hydrogel, and wherein the 3D cell culture plate comprises: a well plate comprising a plurality of main wells and a plurality of sub wells formed at lower portions of the main wells to be injected with a cell culture solution and comprising recessed parts on a bottom surface thereof; and a connector for large-capacity and high-speed high content screening, which supports the well plate, and the connector for high content screening comprises a base equipped with a fixing means so as to be attached to and detached from a lower end of the well plate and a cover positioned on an upper portion of the well plate to be coupled to the base, the main well has a step formed so as to be tapered at a predetermined site, and the step has an inclination angle (θ) ranging from 10 to 60° with respect to a wall of the main well. treating the cultured cancer organoid with an anticancer agent and/or radiation; and selecting the cancer organoid treated with the anticancer agent and/or radiation as a cancer organoid having resistance to an anticancer agent and/or radiation when the cancer organoid treated with the anticancer agent and/or radiation has a viability equal to or more than that before the treatment with the anticancer agent and/or radiation, wherein in the culturing of the organoid, the 3D cell culture plate comprises 0 to 2 vol% of an extracellular matrix-based hydrogel, and wherein the 3D cell culture plate comprises: a well plate comprising a plurality of main wells and a plurality of sub wells formed at lower portions of the main wells to be injected with a cell culture solution and comprising recessed parts on a bottom surface thereof; and a connector for large-capacity and high-speed high content screening, which supports the well plate, and the connector for high content screening comprises a base equipped with a fixing means so as to be attached to and detached from a lower end of the well plate and a cover positioned on an upper portion of the well plate to be coupled to the base, the main well has a step formed so as to be tapered at a predetermined site, and the step has an inclination angle (θ) ranging from 10 to 60° with respect to a wall of the main well. a well plate comprising a plurality of main wells and a plurality of sub wells formed at lower portions of the main wells to be injected with a cell culture solution and comprising recessed parts on a bottom surface thereof; and a connector for large-capacity and high-speed high content screening, which supports the well plate, and the connector for high content screening comprises a base equipped with a fixing means so as to be attached to and detached from a lower end of the well plate and a cover positioned on an upper portion of the well plate to be coupled to the base, the main well has a step formed so as to be tapered at a predetermined site, and the step has an inclination angle (θ) ranging from 10 to 60° with respect to a wall of the main well.