The present invention relates to antibodies specifically binding to native proBNP, a method for specific detection of native proBNP, a method of correlating the level of native proBNP to the diagnosis of heart failure, a kit for detection of native proBNP and to a hybridoma cell line producing an antibody to native proBNP. The p+ impurity region defines a high-potential island region, a low-potential island region and a slit region in the n\u2212 semiconductor layer. The bottom surface forms a surface where, of the light reflected from the work piece, light following a direct reflection direction is reflected in a direction moving away from the incidence region, from a position where light emitted from the emitting region is emitted at the work piece.