The surface modification of poly(p-phenylene terephthalamide) (PPTA) film with 2-aminoethanethiol (AET) to adhere to silicon rubber was investigated. The combination of the AET treatment and the silane coupling treatment is an effective surface modification of the PPTA film for this adhesion. The x-ray photoelectron spectroscopy (XPS) analyses show that the AET treatment does not generate sulfur functionalities at the surface of the PPTA film but does generate oxygen functionalities. In the AET treatment process, a part of the amide groups near the surface of the PPTA film is hydrolyzed to form carboxylic acid groups and amino groups. The oxygen functionalities are condensed at the film surface, and nitrogen functionality is diluted at the film surface. The C(O)O moiety at the PPTA film surface may be a key factor for the adhesion with silicon rubber. The C(O)O moiety is mobile from the bulk of the PPTA film to the film surface. Hot water treatment of the original PPTA film makes the impossible adhesion with the silicon rubber possible. The hot water treatment, however, is not as powerful a surface modification as the AET treatment.