Introduction: Aggregatibacter actinomycetemcomitans (A.a) is the main bacterium that causes aggressive periodontitis which is capable of forming biofilms on the surface of periodontal tissues. The objective of the study of the bacterial biofilm proteins is to provide an alternative to early prevention of oral infection of Periodontitis caused by A.a. Biofilms formed characterized by its molecular weight will then be used for the purpose of making Periodontal Disease Detection Kits. This project is aimed to select the molecular weight of biofilm protein of A.a exposed to 5% glucose, lactose, soy protein, and iron. Methods: Exposure to 5% glucose, lactose, soy protein, and iron is nenecessary to form biofilm of A.a. Then, the biofilm is characterized by SDS-PAGE electrophoresis to measure the molecular weight. Results: From this study A.a biofilm bands were formed with the number of protein bands that varied depending on the induction used. A.a induced by 5% glucose had one protein band (37.5 kDa), A.a induced by 5% lactose had five protein bands (77.9 kDa, 52.6 kDa, 46.8 kDa, 36.6 kDa, and 28.5 kDa), A.a induced by Soy Protein had seven protein bands (77.9 kDa, 71.3 kDa, 47.4 kDa, 40.4 kDa, 37.2 kDa, 28.8 kDa and 11.8 kDa) and A.a induced by 5% iron did not form protein band. Conclusion: Exposure to 5% glucose, lactose, soy protein, and iron to A.a resulted in band of biofilm protein. However, A.a biofilm induced by 5% iron has no protein bands.