Abstract Biofilm control has become an important issue since biofilms cause serious problems such as infections, biocorrosion, and biofouling. Mature biofilms are more tolerant to most disinfectants than the initial state of biofilms; monitoring the initial biofilm formation could be a strategy for effective biofilm control. In this study, we tried to develop a rapid detection system of initial bacterial attachment with interdigitated array (IDA) electrodes and electrochemical impedance spectroscopy (EIS). Pseudomonas aeruginosa PAO1 was used as the model bacterium. An IDA electrode with a 10-μm gap between microband was fabricated to increase the sensitivity of the electrochemical signals. As a result, the double layer capacitance of the IDA electrode rapidly decreased within 1h by bacterial attachment, indicating this signal could be a key parameter for rapid monitoring of initial bacterial attachment. Furthermore, monitoring of initial bacterial attachment was successfully conducted by measuring the double layer capacitance at a fixed frequency (100Hz) over time, suggesting that this technique can be applied to real time monitoring.