To provide a method for heat-treating polyester, which is used for obtaining heat-treated polyester chips, which contain small amounts of gel-state materials and cyclic compounds, from which a fiber, film or hollow molding of excellent quality is obtained and which is suitable for extrusion moldability.

The method for heat-treating polyester comprises the steps of: beforehand putting fines having 40-60% calculated crystallinity in a heat treatment apparatus by 10-80 mg/cm2-inner wall surface area of the heat treatment apparatus; throwing polyester chips into the heat treatment apparatus when the wall temperature is 60-170C; and heat-treating the thrown polyester chips at the temperature equal to or higher than 190C and lower than the melting point of the polyester chip.