To obtain a polymer which gives a molded article excellent in tensile properties, bending properties, impact resistance, and mechanical properties by selecting a thermotropic arom. polymer contg. a plurality of kinds of monomer units.

A thermotropic arom. polymer comprising about 2 to about 45 mol.% monomer units of formula I, about 0 to about 40 mol.% monomer units of formula II, about 5 to about 47 mol.% monomer units of formula E, and about 6 to about 90 mol.% monomer units of formula IV, the sum of amts. of monomer units of formulas I and II being almost equal to the amt. of monomer unit of formula III, is selected. In formulas II to IV, Ar1 to Ar3 are each 1,3-phenylene, 1,4-phenylene, 2,6-naphthylene, 2,7-naphthylene, 4,4'-biphenylene, or a bis-aryl moiety of formula V [wherein X is S, O, CO, SO, SO2, C(CH3)2, or C(CF3)2], the bis-aryl moiety accounting for less than about 50 mol.% of all the Ar1 to Ar3 groups.