Disclosed is a stable tablet 4,5-epoxymorphinan derivative or a pharmacologically allowable acid addition salt thereof as the active ingredient. Specifically, this tablet contains (1) as the active ingredient, a prescribed 4,5-epoxymorphanin derivative or a pharmacologically allowable acid addition salt thereof； (2) sodium thiosulfate； (3) at least one sugar or sugar alcohol selected from a group comprised of sugars and sugar alcohols； and (4) crospovidone, sodium carboxymethyl starch, or a mixture thereof； where the amount of the aforementioned (4) that is included is 1-20 wt% per unit weight of the aforementioned contained active ingredient.
