A surface plasmon-field enhanced fluorescence spectroscopy [SPFS] sensor chip comprising: a transparent support, a metal thin film formed on one surface of the transparent support, a self-assembled monolayer formed on a surface of the metal thin film, said surface not being in contact with the transparent support a solid phase layer formed on a surface of the SAM and having a three-dimensional structure, said surface not being in contact with the metal thin film, wherein the solid phase layer contains a hydrophilic polymer, and a ligand immobilized in the solid phase layer, characterized in that the SPFS sensor chip has a fluctuation ratio, represented by the following formula, in the range from 0 to 30 %, half − width α − half − width β / half − width β × 100 wherein (i) the solid phase layer has a density of less than 2 ng/mm 2; (ii) the solid phase layer has a mean film thickness of 3 to 80 nm; (iii) the density of the ligand immobilized in the solid phase layer is in the range from 10 femto-mol/cm 2 to 100 pico-mol/cm 2; (iv) the half-width (α) is a half-width obtained from a graph on which a quantity of reflected light of light entering one surface of the transparent support at a prescribed angle, the surface not being in contact with the metal thin film, as measured by a light quantity detector placed on the other surface side of the transparent support, is plotted against the angle, and the half-width (β) is a half-width of a substrate that is the SPFS sensor chip including the transparent support and the metal thin film formed on one surface of the transparent support but not including the SAM, the solid phase layer and the ligand. a transparent support, a metal thin film formed on one surface of the transparent support, a self-assembled monolayer formed on a surface of the metal thin film, said surface not being in contact with the transparent support a solid phase layer formed on a surface of the SAM and having a three-dimensional structure, said surface not being in contact with the metal thin film, wherein the solid phase layer contains a hydrophilic polymer, and a ligand immobilized in the solid phase layer, characterized in that the SPFS sensor chip has a fluctuation ratio, represented by the following formula, in the range from 0 to 30 %, half − width α − half − width β / half − width β × 100 wherein (i) the solid phase layer has a density of less than 2 ng/mm 2; (ii) the solid phase layer has a mean film thickness of 3 to 80 nm; (iii) the density of the ligand immobilized in the solid phase layer is in the range from 10 femto-mol/cm 2 to 100 pico-mol/cm 2; (iv) the half-width (α) is a half-width obtained from a graph on which a quantity of reflected light of light entering one surface of the transparent support at a prescribed angle, the surface not being in contact with the metal thin film, as measured by a light quantity detector placed on the other surface side of the transparent support, is plotted against the angle, and the half-width (β) is a half-width of a substrate that is the SPFS sensor chip including the transparent support and the metal thin film formed on one surface of the transparent support but not including the SAM, the solid phase layer and the ligand. (i) the solid phase layer has a density of less than 2 ng/mm 2; (ii) the solid phase layer has a mean film thickness of 3 to 80 nm; (iii) the density of the ligand immobilized in the solid phase layer is in the range from 10 femto-mol/cm 2 to 100 pico-mol/cm 2; (iv) the half-width (α) is a half-width obtained from a graph on which a quantity of reflected light of light entering one surface of the transparent support at a prescribed angle, the surface not being in contact with the metal thin film, as measured by a light quantity detector placed on the other surface side of the transparent support, is plotted against the angle, and the half-width (β) is a half-width of a substrate that is the SPFS sensor chip including the transparent support and the metal thin film formed on one surface of the transparent support but not including the SAM, the solid phase layer and the ligand.