A new type propeller derived from “winglets” was investigated. This propeller is also fitted small blades at the blade tips likely to “winglets”, so we named it “bladelets”. These are for the purpose of reducing induced drag from tip vorteces. This paper, as the first report, mainly presents the results of the series tests which are concerned with the arrangement of these small blades. Propeller open test, flow visualization and flow velocity measurements were performed, and one of the best arrangement of “bladelets” were found out. The results looks 1 or 4% better compared the efficiency of “bladelet propeller” with that of the original one within the bound of real working condition.