An alumina slurry containing alumina dispersed in a dispersion medium, the alumina having an average primary particle diameter of 0.1 μm or more and 1.0 μm or less, the alumina satisfying the following condition (1), and the slurry having a content of the alumina of 30% by mass or more and 70% by mass or less and a content of water in the dispersion medium of 50% by mass or more:condition (1): in relationship of a pore diameter r1 (Å) and a pore volume Dv1 (mL/g) of the alumina measured by a nitrogen desorption method based on JIS Z8831-2 (2010), the pore volume Dv1(80) at r1=80 and the maximum value Dv1(M) of Dv1 in a range 20≤r1≤80 satisfy Dv1(M)>Dv1(80).