To produce a polyester having a high transparency and pref. usable for producing a hollow vessel by solving the problems posed in the production of a polyester for a hollow vessel by using antimony trioxide and phosphoric acid.

A polyalkylene terephthalate having a limiting viscosity of 0.70 or above or a polyester mainly comprising it is produced by esterification, melt polycondensation, and solid-phase polymn. 0.2 to 2wt.% solution of phosphoric acid in an alkylene glycol is added to an oligoester having an average degree of polymn. of not higher than 10 in such an amount that 1×10-4 to 1×10-3mol of phosphoric acid is used per mole of the acid component of the polyester. The reaction is conducted at 200 to 280°C for 0.5 to 4h. An antimony compd. is added as a polycondensation catalyst to effect melt polycondensation and solid-phase polymerization.