Silicon carbide epitaxial substrate and silicon carbide semiconductor device

A silicon carbide epitaxial substrate (3) constituting a silicon carbide semiconductor device (100) is provided with: a silicon carbide substrate (10), which has an impurity concentration equal to or higher than 3×10 18 cm -3 , and has an off-angle exceeding 0°; and an active layer (11). A first epitaxial layer (20), a second epitaxial layer (21), and a third epitaxial layer (22) of the active layer (11) satisfy the relationship of N1≤1×10 16 cm -3 , N2≥1×10 17 cm -3 , N3≤1×10 16 cm -3 , T2≥0.01 μm, and T1×T2×N2≤2.684×10 17 , where the layer thicknesses of the epitaxial layers are respectively represented by T1 [μm], T2 [μm], and T3 [μm], and the impurity concentrations thereof are respectively represented by N1 [cm -3 ], N2 [cm -3 ], and N3 [cm -3 ].