The composition of free amino acids in the whole body of non-overwintered larvae and overwintered larvae of the chestnut weevil, Curculio dentipes (Roelofs) was examined by means of High-speed amino acid analyzer. A total of 14 free amino acids was found in both stages, which were alanine, arginine, glutamic acid, glycine, histidine, isoleucine, leucine, Iysine, phenylalanine, proline, serine, threonine, tyrosine and valine. In non-overwintered larvae, glutamic acid was predominent amino acid, and histidine, alanine, threonine and valine were shown to have high concentration. Also, alanine was the highest concentration amino acid, and the levels of alanine, glutamic acid, Iysine, valine and threonine were abundant amino acid in overwintered larvae. Proline content was the least amount in both stages. Except for leucine and histidine, other amino acids were accumulated during the winter. Alanine, Iysine, glycine, glutamic acid and valine especially were increased markedly. Ammonia in overwintered larvae showed a rise of almost double amount than in non. overwintered larvae. For significance level 1%, there exist differences between two population non-overwintered larvae and overwintered larvae. Therefore, the mean of amino acids in overwintered larvae is larger than that of amino acids in non-overwintered larvae.