PURPOSE: To obtain a new cholesterol derivative, capable of acting as an anchor on a lipid membrane and binding the lipid membrane to a biological substance and useful for immunodiagnosis, medical applications, medicines, etc., by condensing a halogenopyridine with cholesterol in the coexistence of a suitable base.

CONSTITUTION: This new cholesterol derivative is expressed by formula I (X and Y are each H, a halogen, NO2, NH2 or N=C=S; the bond composed of a broken line and a solid line between the 5- and the 6-positions of the steroid skeleton indicates single or double bond) or a quaternary ammonium salt thereof. The cholesterol part is capable of acting as an anchor on a lipid membrane such as a cell or a liposome membrane and binding the lipid membrane to a biological substance such as a protein, a nucleic acid or a glucide. The cholesterol derivative is useful in the field of immunodiagnosis, medical applications, medicines, etc. This compound is obtained by a method for condensing 2- bromo-5-nitropyridine, etc., with cholesterol expressed by formula II in the coexistence of a suitable base, then reducing the nitro group, isothiocyanating the resultant reduced group, etc.