An aluminum foil provided by the present invention has a first principal surface (1A) and a second principal surface (1B) located opposite the first principal surface (1A). In at least one of the first principal surface (1A) and the second principal surface (1B), the surface roughness Ra is 10 nm or smaller, and the surface roughness Rz in the rolling direction (X) and the surface roughness Rz in the direction (Y) perpendicular to the rolling direction (X) are both 40 nm or smaller. Moreover, a peak count value calculated from a roughness curve in at least one of the rolling direction (X) and the direction (Y) perpendicular thereto is 10 or larger when the reference length (L) is set to 40 micrometers.