A water stop structure is provided for a wire harness connected to an electronic control unit installed in an automotive vehicle or a motorcycle. Specifically, a resin composition containing a cyclic phosphorus compound flame retardant, a hydrophilic silica powder having an average particle diameter of not more than 15 m, and a resin with the total content of the cyclic phosphorus compound and the hydrophilic silica powder being 10-45% by mass is molded into a certain shape or formed into a coating film. 0022\xb0mm exhibits little bending deformation even at a thickness of 1 mm or more, and therefore, is beneficially used as a substrate for a luminescent device. A controller linked to the rotating system thereafter may receive a signal that the transfer of mass has been detected, in response to detecting the transfer of mass, thereby permitting the controller to compensate future mass placements in the rotating system according to measured latencies.