Provided is a printing plate cylinder to which a sleeve printing plate is detachably attached. In the printing plate cylinder, weight reduction and radiation performance can be improved, and generation of rust can be suppressed. The printing plate cylinder (1) includes a shaft portion (3) rotatable about a central axis (O), a tubular portion (5) formed cylindrically, arranged coaxially with the shaft portion (3), and arranged at a distance from an outer circumferential surface (3a) of the shaft portion (3), and a rib (7) fixed integrally to the outer circumferential surface (3a) of the shaft portion (3) and an inner circumferential surface (5b) of the tubular portion (5) and connecting the shaft portion (3) and the tubular portion (5). An air supply channel (31) is formed so as to penetrate from the outer surface of the rib (7) exposed to the outside to the outer circumferential surface (5a) of the tubular portion (5).