PURPOSE: To obtain a polyurethane composition with superior physical and mechanical properties by reacting a polyisocyanate, a polyol, a specified chain extender and a catalyst.

CONSTITUTION: A polyurethane composition is prepared by reacting a polyisocyanate, a polyol, a chain extender having a non-escaping catalytic action and comprising a diaminobenzoate to which side chain a tertiary amine functional group of the formula is introduced [wherein, Y is R1NR2R3, R1NR4NR5, R1NR4O, R1NR1R2NR2R3; R1 is (CH2)n; (n) is 2 to 5; R2, R3 and R6 are each a 1-4C alkyl, a 1-4C alkoxy; R4 is a cyclic crosslinking group forming a 5 to 7 membered ring; R5 is H or R2] and a catalyst.