A new piperidine compound is pharmacologically effective for treatment of the arrythmia and is defined by the formula: ##STR1## in which R.sup.1 is a lower alkyl or a tolyl, R.sup.2 is hydrogen, hydroxyl, a lower alkoxy or a lower alkyl, R.sup.3 is hydrogen, a lower alkyl, a lower alkenyl, a cycloalkyl or a cycloalkylalkyl, X is --CO--, --CH.sup.2 -- or --CHOH--, g is an integer of 1 to 3, h is an integer of 1 to 3, Y is hydrogen, a lower alkyl, a lower alkenyl, cyano, CH.sup.2 COOR, R being hydrogen or a lower alkyl, a cycloalkyl, a cycloalkylalkyl, ##STR2## 1 being 1 or 2, --A--B, A being --(CH.sub.2).sub.n --, n being an integer of 1 to 5,a straight-chain alkylene group having 1 to 5 carbon atoms which is a divalent group derived from a straight-chain alkane having lower alkyl, phenyl or hydroxyl group(s) bonded directly to one or more carbon atoms constituting said alkane by removing a hydrogen atom bonded to each of the carbon atoms placed at both ends thereof,a straight-chain alkylene group having 1 to 5 carbon atoms which is a divalent group derived from a straight-chain alkene having a double bond formed between carbon atoms adjacent to each other by removing a hydrogen atom bonded to each of the carbon atoms placed at both ends thereof,--(CH.sub.2)k--S--, k being an integer of 2 to 5, --(CH.sub.2)p--CO--, p being an integer of 1 to 4, B being cyano, --NR.sub.4 R.sub.5, a heterocyclic ring or a condensed aromatic ring.