This paper deals with the development of a new mechanism assisting a standard hand-propelled wheelchair in driving over a higher step.According to the measurement method presented, experimental results are given as the values of resistant force against various steps and possible power of nine male operators.The basic design of the proposed mechanism is illustrated, and its prototype is manufactured.The results from several experiments demonstrate that this prototype is able to drive over the step whose height can not be overcome by a standard wheelchair.It is, therefore, shown that the proposed mechanism is effective for driving over a higther step.