The present invention relates to a stable tablet comprising a 4,5-epoxymorphinan derivative or a pharmacologically acceptable acid addition salt thereof as an effective ingredient. That is, the tablet according to the present invention comprises: (1) as the effective ingredient, a specific 4,5-epoxymorphinan derivative or a pharmacologically acceptable acid addition salt; (2) sodium thiosulfate; (3) at least one selected from the group consisting of saccharides and sugar alcohols; and (4) crospovidone, sodium carboxymethyl starch or a mixture thereof, in which tablet the content of the aforementioned (4) is 1 to 20% by weight per unit weight containing the aforementioned effective ingredient.