Electrochemoluminescent detector for analyzing a biochemical or biological substance, comprising at least a cell (11, 12) generating and detecting the electrogenerated chemoluminescence, which includes: at least a working electrode (16, 17) produced on a substrate (20); electric power supply (13) connected to the electrode; a photodiode (14) detecting the light generated by electrochemoluminescence; and a device for measuring the signal delivered by the photodiode. The photodiode (14) is produced by being integrated in the substrate (20). The cell comprises two interdigital working electrodes protected by a passivation layer (18) leaving part of their top surface in contact with outside. An intermediate layer (19) of dielectric material is inserted between the electrodes and the substrate (20).