Tb7Fe90B3 microwires with a diameter of 50-100 μm were obtained by the method of ultrafast cooling of the melt. It has been established that the microwires contain the tetragonal Tb2Fe14B1 phase and the cubic TbFe3 phase. These two phases differ in saturation fields of 100 Oe and 10 kOe, respectively. The anisotropy of the coercive force of TbFeB microwires also indicates the coexistence of two magnetic phases. The data obtained are compared with the magnetic properties of PrDyFeCoB microwires, in which the coercive force is isotropic, and magnetization saturation is achieved in lower fields.