Biaxially stretched polyester film

A biaxially stretched polyester film comprising a polyester A layer and a polyester B layer, wherein

• the polyester A layer comprises a polyester resin (I) and a polyester resin (II),
• the polyester B layer comprises the polyester resin (I) and the polyester resin (II),
• the polyester resin (I) comprises (a) terephthalic acid or an ester-forming derivative thereof and (b) ethylene glycol as main constituent components, wherein the terephthalic acid or an ester-forming derivative thereof or the ethylene glycol is derived from a biomass resource,
• the polyester resin (I) has a degree of biomass measured according to ASTM D6866 of 10% or more,
• the polyester resin (I) has a recrystallization temperature obtained by DSC of 160° C. or more and 193° C. or less when the polyester resin (I) is cooled from the molten state at −10° C./min,
• the polyester resin (II) has a recrystallization temperature obtained by DSC when the polyester resin (II) is cooled from the molten state at −10° C./min that differs from the recrystallization temperature of the polyester (I),
• the polyester resin (I) is contained in an amount of 60 mass % or more based on 100 mass % of the entire film,
• the film has a tensile modulus of elasticity in a longitudinal direction of 3200 MPa or more and a tensile modulus of elasticity in a width direction of 3200 MPa or more, and
• the tensile modulus of elasticity in the longitudinal direction and the tensile modulus of elasticity in the width direction provide a sum total tensile modulus of elasticity of 7000 MPa or more.