A galactosamine derivative represented by the following formula (1): wherein R.sub.1, R.sub.2 and R.sub.5 each independently represents SO.sub.3.sup.- or H, and at least one of them represents SO.sub.3.sup.-; R.sub.3 represents H, acetyl or SO.sub.3.sup.-; R.sub.4 represents H, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group; X represents O, S, NH or CH.sub.2; and represents an .alpha. bond or a .beta. bond, and a sulfotransferase inhibitor comprising the derivative.