To obtain a new 4-hydroxyphenylcarbamic acid compound, useful as a fluorescent substrate, used for determining a peroxidase, etc., and having a high detection sensitivity, reactive with hydrogen peroxide in the presence of the peroxidase, dimerizing and converting into the fluorescent substance.

This compound is expressed by formula I (R1 is an alkyl, etc.; R2 is an alkyl), e.g. 4-(N-methoxycarbonyl-N-methylamino)phenol. The compound is obtained by reacting 4-methylaminophenol with a compound of formula II (X is F, Cl, etc.) and then reacting the resultant compound of formula III with a compound of formula IV(Y is a halogen of F, Cl, Br or I or an eliminative group such as p-nitrophenoxy).