NEW MATERIAL:An amizine derivative of formula I (R is H, lower alkyl, or OH; m and n are 1-3; R1 is lower alkyl, halogeno-lower alkyl, OH, etc.; R2 is H, lower alkyl, lower alkenyl, etc.) and its acid addition salt. EXAMPLE:N-Sulfamoyl-3-[(2-guanidinothiazol-4-yl)methylthio]propionamiz ine. USE:A gastric juice secretion suppressing agent. The mechanism of the action is not cholinergic. Administrable orally or parenterally. PROCESS:The compound of formula I is prepared either by the reaction of a compound of formula II1 (R' is lower alkyl) with an amine of formula III1, or the reaction of a compound of formula II2 with an amine of formula III2. The reactions are carried out in a solvent such as alcohol, etc., at room temperature or with heating.