A clathrate or containment compound comprising a tetrakis phenol compound represented by general formula [I] as "host" compound and a 2-alkyl-3 (2H) isothiazolone as "guest" compound, wherein X represents (CH 2 n, n represents 0, 1). or 2, and R 1 to R 2 each represent independently hydrogen, lower alkyl, halogen, lower alkoxy or optionally substituted phenyl.