A method of analyzing interactions between first proteins and second proteins at a single molecular level, comprising: (a) preparing at least two substrates, in which first protein-binding molecules that are biomolecules to be bound to the first proteins are attached to each of the substrates; (b) inducing binding between the first proteins and the first protein-binding molecules on the first substrate and the second substrate, respectively, by supplying the first proteins included in the control group-cell to the first substrate among the two substrates and supplying the first proteins included in the experimental group-cell to the second substrate among the two substrates, wherein the concentration of the control group cell should be equal to the concentration of the experimental group cell; (c) supplying cell lysates of cells including the marker-tagged second proteins to the first substrate and the second substrate, respectively, when the first proteins and the first protein-binding molecules are bound to the first substrate and the second substrate, respectively, wherein the concentration of the second proteins in the cytoplasmic cell lysates to be supplied to the first substrate and the second substrate, respectively, should be the same as each other; and (d) comparing and analyzing the interactions between the first proteins and the second proteins on the first substrate and the second substrate in the supply of the cell lysates to the first substrate and the second substrate, respectively; wherein the step (d) includes measuring a fluorescent signal having a specific wavelength generated by the markers tagged to the second proteins bound to the first proteins using an optical apparatus generating a near-field, wherein in the step (b), the control group-cell is a normal cell and the experimental group-cell is a tumor cell, wherein in the step (d), the fluorescent signal having the specific wavelength is cumulatively measured for a predetermined time period. (a) preparing at least two substrates, in which first protein-binding molecules that are biomolecules to be bound to the first proteins are attached to each of the substrates; (b) inducing binding between the first proteins and the first protein-binding molecules on the first substrate and the second substrate, respectively, by supplying the first proteins included in the control group-cell to the first substrate among the two substrates and supplying the first proteins included in the experimental group-cell to the second substrate among the two substrates, wherein the concentration of the control group cell should be equal to the concentration of the experimental group cell; (c) supplying cell lysates of cells including the marker-tagged second proteins to the first substrate and the second substrate, respectively, when the first proteins and the first protein-binding molecules are bound to the first substrate and the second substrate, respectively, wherein the concentration of the second proteins in the cytoplasmic cell lysates to be supplied to the first substrate and the second substrate, respectively, should be the same as each other; and (d) comparing and analyzing the interactions between the first proteins and the second proteins on the first substrate and the second substrate in the supply of the cell lysates to the first substrate and the second substrate, respectively;