An endless retainer for a guiding device comprising a multiplicity of rolling bodies disposed at predetermined intervals and adapted to roll on an endless track formed in the guiding device and flexible resin connecting bodies having an interposing portion interposed between the respective rolling bodies and a connecting portion for connecting the interposing portions for holding the rolling bodies in an aligned and rollable state, wherein the resin connecting body is formed by injection molding using a resin having a dimensional changing before and after an oil or water absorption process greater than the molding shrinkage with the rolling body serving as a core, and wherein there are provided gaps between the rolling bodies and the resin connecting body that are formed through the oil or water absorption process, whereby since there is no risk of the rolling bodies coming off, the retainer is easy to handle. In addition, with this configuration, it is possible not only to automatically install the retainer in the guiding device but also to securely provide the extremely smooth rotation to the rolling bodies.