To provide a semiconductor substrate for manufacturing a vertical type device, in which a low ON-resistance of a vertical type MOSFET or the like is maintained, whereas a needed OFF breakdown strength can be ensured.

This semiconductor substrate is constituted, such that a high density arsenic layer 12 having a thickness of 0.5 to 3.0 μm is inserted in between a high density phosphorus layer 11 constituting the drain of the vertical-type MOSFET and an n-type drift layer 13. Thus, since the high-density arsenic layer 12 functions as a barrier layer which prevents phosphorus from spreading, from the high density phosphorus layer 11 to the n-type drift layer 13, the spread of a depletion layer, when turning off in the vertical-type MOSFET is ensured to enhance an OFF breakdown strength, and also the low ON resistance can be maintained.