Collagen fibril membranes (CFMs) with a high mechanical property were fabricated with a lateral face evaporation method, in which type I atelocollagen extracted from tilapia scales was used. The density and thickness of the CFM obtained were 0.51 ± 0.04 mg/cm 3 and 50 ± 5 μm. The collagen fibrils in the CFM had a similar periodic stripped pattern of 67 nm with native collagen fibrils. The CFM was crosslinked in gaseous glutaraldehyde for different duration in order to increase the mechanical property. The crosslinking degrees of the CFMs analyzed by free amino groups gradually increased to 70.3 % against the exposure duration until 6 hours, and reached a plateau. The denaturation temperatures of the CFMs with the crosslinking degrees at 20.4 % to 43% were linearly increased from 49°C to 75°C. The tensile strength of the CFMs was slightly improved until the crosslinking degree at 33.3 % and then the tensile strength rapidly increased to be 68 MPa. It was suggested that a percolation phenomenon took place in the CFMs by crosslinking of collagen fibrils with polymerized GA molecules.