Collagen peptide (ColP), which was extracted from fish scale with hot water was mixed with glutaraldehyde (GA) in water in the presence of sodium montmorillonite (MMT), and subsequent heat treatment gave the ColP crosslinked by GA (GA-ColP)/MMT composite films. Also, the ColP was chain extended by the use of a water-soluble carbodiimide and 1-hydroxybenzotriazole to give a chain-extended collagen pepticle (CE-ColP). The composite films based on the CE-ColP and MMT were prepared by solution-casting method. The XRD and TEM analyses of their composites revealed that the exfoliated nanocomposites whose silicate layers are finely dispersed are formed for CE-ColP/MMT, and that the degree of exfoliation decreases with the increasing feed amount of GA for GA-ColP/MMT. Although GA-ColP/MMT films were very brittle, CE-ColP/MMT films were relatively tough. Storage moduli of the CE-ColP/MMT films were higher than that of CE-ColP film, and increased with increasing inorganic content. The 10% weight loss temperature of GA-ColP (325 degrees C) was higher than that of CE-ColP (302 degrees C), and the addition of MMT to GA-ColP and CE-ColP resulted in a slight rise of the degradation temperature.