A method for manufacturing a single-crystal 4H—SiC substrate includes preparing a 4H—SiC bulk single-crystal substrate having a flat surface, and growing an epitaxial first single-crystal 4H—SiC layer having recesses on the 4H—SiC bulk single-crystal substrate to a thickness X, measured in micrometers (μm). The recesses have a diameter Y, measured in micrometers, no smaller than 0.2*X and no larger than 2*X. In addition, the recesses have a depth Z, when measured in micrometers, no smaller than (0.95*X+0.5*10−3), and no larger than 10*X*10−3.