The criteria for a mesenchymoma are that it should be composed of at least two mesenchymal elements not ordinarily found together in a tumor. This report dealt with two cases of benign mesenchymoma arising, one in the left thigh and the other in the left forearm. To diagnose of this tumor on X-ray preoperatively was difficult. The tumors were excised as much as possible, and mesenchymal derivatives characteristic of the tumor was described in detail.