A 1,2-dioxetane derivative of formula (I): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 are each independently a hydrogen atom, an alkyl group, or an aryl group, R.sup.2 and R.sup.3 together and R.sup.4 and R.sup.5 together can be joined as a cyclo-alkyl group, R.sup.6 is a hydroxyl group, an alkoxyl group, an aralkyloxy group, --OSi(R.sup.8 R.sup.9 R.sup.10) in which R.sup.8, R.sup.9 and R.sup.10 are each independently an alkyl group, or a phosphate salt, and R.sup.7 is a hydrogen atom, a halogen atom, an alkyl group, or an alkoxyl group.