Problem to be solved: to provide a polyester film having both a hydrolyzable property and a visible light concealment and a good surface shape, and to suppress generation of stimulating gas in the manufacturing process. The present invention relates to a polyester resin composition comprising a compound represented by the following formula (1), a pigment and a polyester. The present invention relates to a master pellet, a polyester film, a back sheet for a solar cell module, and a solar cell module. In formula (1) R2 may be an alkyl group that may have a substituent, a cycloalkyl group that may have a substituent, an aryl group that may have a substituent or an alkoxy group that may have a substituent, and R3 may be a specific alkyl group or Represents aryl groups, and R11, R12 and R13 independently represent hydrogen atoms, an alkyl group or a group of aryl groups having a substituent.
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