The present invention relates to provision of: a fluorescent dye compound having a benzotriazole derivative that is a novel compound having high processability, desired optical characteristics and good photostability, while being suppressed in the formation of a precipitate; a fluorescent dye polymer compound having a benzotriazole structure; and a wavelength converting sealing material composition which uses the fluorescent dye polymer compound. The present invention also relates to provision of: a wavelength converting sealing material layer which is formed using the wavelength converting sealing material composition, and which has desired optical characteristics and good photostability, while being suppressed in the formation of a precipitate; and a photovoltaic module which comprises the wavelength converting sealing material layer. A polymer fluorescent dye compound represented by general formula (I). (In the formula, each of X1 and X2 independently represents -O-, -(C=O)O-, -O(C=O)-, -CH2O-, -CH2O(CO)-, -NH(CO)-, -NR-CH2- or a single bond, and R represents an alkyl group having 1-8 carbon atoms; each of Y1 and Y2 independently represents an optionally substituted alkyl group having 1-18 carbon atoms, or the like; P represents a polymer structure moiety; L represents a linker structure moiety that bonds a benzotriazole ring and the polymer structure moiety by a covalent bond; each of Z1 and Z2 independently represents an optionally substituted alkyl group having 1-18 carbon atoms, or the like; and each of m, n, o and p independently represents an integer of 0-4.)