To provide an anisotropic electroconductive adhesive sheet achieving good electrically coupling performance without impairing the electrical insulation of spaces among circuits and fine circuits adjacent thereto.

The anisotropic electroconductive adhesive sheet including at least: a curing agent; a curable electrical insulation resin; and electroconductive particles; is provided. In the adhesive sheet, in a region ranging from the one-side surface of the adhesive sheet along the thickness direction to a position of equal to or less than 1.5 times the average size of the electroconductive particles, 90% or more of the sum of the electroconductive particles are present, and the 90% or more of the electroconductive particles are present without contact with the other electroconductive particles. The average size of the electroconductive particles is 1-8 μm; the average particle distance among adjacent electroconductive particles is ≥1 to ≤5 times the average size thereof but is ≤20 μm; the arrangement pattern of the particles in the planar direction represents a nearly triangular lattice; and the thickness of the anisotropic electroconductive adhesive sheet is twice or greater the average particle distance but is ≤40 μm.