To obtain a liquid injection sealing underfill material for semiconductor packages that does not cause exfoliation and cracks even in pressure cracker test and thermal cycle test.

This liquid injection sealing underfill material contains, as main components, (a) a liquid epoxy resin, (b) an aromatic amine-based curing agent, an alkylated diaminodiphenylmethane, (c) a silane coupling agent having one or more functional groups selected from epoxy, amino and mercapto groups in one molecule, and (d) an inorganic filler having a specific particle size distribution, in such conditions that compounding ratios of respective components by weight is in relationships of (c)/[(a)+(b)+(c)]=0.01 to 0.05 and (d)/[(a)+(b)+(c)+(d)]=0.50 to 0.80, and that the inorganic filler has an average particle size of 4-6μm, and contains 20-70wt.% of particles of 1μm or smaller size, and 30wt.% or less of particles of 30μm or larger size up to 50μm, with larger particle sizes than 50μm cut out.