PURPOSE: To obtain the title substance simply and in high yield, to regenerate hydrogen iodide from iodine prepared as a by-product and to reuse hydrogen iodide, by reacting an aromatic sulfonyl halide or aromatic sulfinic halide or aromatic sulfinic acid with hydrogen iodide in the presence of hydrogen sulfide.

CONSTITUTION: 1 mol of a compound shown by formula I (R is H, OH, alkyl, alkylthio, acetyl, halogen or phenyl; X is H or halogen) is reacted with 0.0005-1.0 mol hydrogen iodide in the presence of 1.5-10.0 mol HS to give a compound shown by formula II (n is 2-8). Or 1 mol of a compound shown by formula III(A is single bond, S or S-S; Y is H or halogen) is reacted with 0.001-2.0 mol hydrogen iodide in the presence of 3.0-20.0 mol HS to give a compound shown by formula IV (y is 2-8; z is ≥1 integer). The reaction temperature is 10-150°C in both the reactions. The prepared aromatic polysulfide is useful as an intermediate for producing an aromatic thiol.