Breakdown fields along 4H-SiC <11<(2)over bar>0>, 4H-SiC <03<(3)over bar>8>, 6H-SiC <0<(1)over bar>1 (4) over bar>, and 3C-SiC <001> were measured using p(+)n diodes with mesa structure. It was found that the breakdown fields along these directions are about 75% of that along 4H-SiC <0001> For 3C-SiC, the breakdown field was preliminarily estimated, but the actual one might be somewhat higher, because relatively low blocking yield made it difficult to perform stochastic measurements.