A polyoxalate containing, as a chief constituent unit, a recurring unit represented by the following formula (1): €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ-(-CO-CO-O-A-O-) n -€ƒ€ƒ€ƒ€ƒ€ƒ(1) wherein n is a positive number, and A is a divalent organic group, and having a quantity of heat of fusion ”Hm of not less than 60 J/g as measured by the DSC in the first time of elevating the temperature and as calculated by the following formula: ”Hm = ”Hm €² ˆ’”Hc wherein, ”Hm' is a quantity of heat of fusion (J/g) inclusive of heat of crystallization while the temperature is being elevated, and ”Hc is a quantity of heat (J/g) generated by the crystallization, permitting the components to be volatilized in an amount of not more than 2.0% by weight when the temperature is elevated up to 200°C as measured by the TGA, and having a 5% weight loss temperature (Td5%) of not higher than 230°C, and a process for the production thereof. The polyoxalate exhibits a highly hydrolysable capability even at low temperatures, can be excellently crushed, i.e., is capable of effectively preventing itself from undergoing the blocking when it is being crushed.