A spherical alumina powder, wherein D50 is 0.1 to 40 m; a circularity is 0.90 or more and 1.00 or less; an -phase percentage is 60% or more and 100% or less; and a particle surface roughness represented by Equation (1) below is 1.14 or more and 1.35 or less:

[00001]$\begin{array}{cc}\mathrm{Particle}\mathrm{surface}\mathrm{roughness}=\mathrm{BET}\mathrm{specific}\mathrm{surface}\mathrm{area}A/\mathrm{sphere}-\mathrm{equivalent}\mathrm{specific}\mathrm{surface}\mathrm{area}\mathrm{Sa}\mathrm{calculated}\mathrm{from}\mathrm{particle}\mathrm{size}\mathrm{distribution}.& \mathrm{Equation}\left(1\right)\end{array}$