Collagen and Polylactic Acid (PLA) as biomaterials in the tissue engineering have been investigated for the structure and function in considerably large progress. From a viewpoint of its electronic structures in the subnano-meter range, we investigate the bonding nature for five models of the type I collagen, PLA models and the bimolecular interaction between the models by using Density Functional Theory (DFT) calculations with Frontier MO theory. In order to confirm the accuracy of the models, we compare the simulated IR and C1s X-ray photoelectron spectra with experimental results. Especially, the interaction between PLA and (AspHypGly)-collagen models was obtained as the chemical bond energy (1540 kJ/mol), and the results of PLA-other four collagen bimolecular models were given as intermolecular bond energies of 30 ∼ 81 kJ/mol. The intermolecular interaction is due to inter-H-bond of –OH---O=, -NH---O=, and –CH---O= functional groups, respectively, using MO calculations.