X-ray structure analysis was carried out in order to clarify the crystal structure and structural disorder of poly-(p-phenylenebenzobisthiazole). Two molecular chains pass through an oblique unit cell with parameters a = 11.60 Angstrom, b = 3.588 Angstrom, gamma = 92.0 degrees and the plane group p2. The angle between the phenylene and benzobisthiazole rings was estimated as 20.5 degrees. Poly-(p-phenylenebenzobisthiazole) includes the disorder with respect to the molecular height, because the first and third layer lines are diffuse streak. On the ac plane, the molecular heights are disordered by 1/2 because 102, 602, and 404 reflections can be observed. On the be plane, the molecular heights are disordered by every 1/5 because the 015 reflection can be observed.