PURPOSE: To obtain an acridan derivative useful as a chemiluminescent compound excellent in stability and as a detecting agent for various diagnostics, various luminous probes, light sources, etc., for emergency.

CONSTITUTION: This acridan derivative is expressed by formula I [R1 and R2 are each H or methyl; (n1) is an integer of 2 to 10; X1 is O atom or S atom; Y is an eliminable group of formula II [X' is O atom or S atom; R3 is a 1-3C alkyl; (n2) is an integer of 0 to 5], etc.], e.g. 10-N-methyl-9- methacryloyloxyethyloxy-9-phenoxycarbonylacridan. The compound of formula I is obtained by reacting, e.g. a (meth)acrylic acid derivative of formula III with an acridine derivative quaternary ammonium salt of formula IV (R6- is an anion) in the presence of a base. Furthermore, chemiluminescence of an acridan derivative of formula I can be carried out by successively treating the acridan derivative of formula I with e.g. an acid, H2O2 and a base.