Spiro[cyclopropane-1,2'-indolin]-3'-ones of the general formula: ##STR1## wherein the ring A is a substituted or unsubstituted phenyl ring and Z is hydrogen, a substituted or unsubstituted alkyl group or a substituted or unsubstituted acyl group and their pharmaceutically acceptable salts have gastric acid secretion suppressing activity, antiinflammatory activity and analgesic activity.