A resin sheet is made using a resin composition containing a thermosetting component (A) and a thermally conductive filler (C). The thermosetting component (A) contains a maleimide resin. A thermal diffusion rate of the thermally cured resin sheet is 1.0×10−6 m2/s or more. When a cross section (P) of the resin sheet taken by cutting the resin sheet in a vertical direction to a surface of the resin sheet is observed in an area (P1), a condition represented by a numerical formula (F1) below is satisfied, the area (P1) being defined by a square whose sides are four times as large as a thickness of the resin sheet and including two surfaces of the resin sheet, 0.25≤Ld/Lt≤1  (F1) where Ld is a vertical length of a filler particle having a largest cross-sectional diameter in the vertical direction of the thermally conductive filler (C), and Lt is a length of the resin sheet.