PROBLEM TO BE SOLVED: To provide a homogeneous assay method improved in SB ratio and through-put in biological molecule measurement using fluorescence. SOLUTION: An electric dipole moment 30 is induced in biological molecules 11 to be quantified, and electric fields E1, E2, E3 modulated in direction are applied thereto to perform fluorescence measurement. Fluorescence from fluorescent molecules forming a composite body 13 with the molecules to be quantified changes in fluorescence intensity in synchronization with the modulation electric field, while fluorescence intensity from uncoupled fluorescent molecules changes at random. A high SB ratio is obtained by utilizing such a phenomenon that the amplitude or phase of fluorescence intensity modulation in the fluorescent molecules coupled with the molecules to be quantified is different from that in the fluorescent molecules not coupled therewith. COPYRIGHT: (C)2013,JPO&INPIT
