A concept of cylindrical deployable space structures is proposed in this paper. Two types of cylindrical deployable space structures which can deploy both axial and radius directions simultaneously are investigated. One is the mirror symmetric type, and the other is the rotationally symmetric one. The basic formulas for the geometry are derived to examine the deployment and packaging characteristics. Non-dimensional width (W/R_0), packaged radius (R/R_0), and angle of apex (θ) are expressed in terms of the geometrical parameters. The feasibility for some applications with the cylindrical deployable "space structures is examined for space development. Finally, this study has shown that the concept is available for the requirements of deployable space structures.