Compounds useful as GnRH receptor antagonists are provided. The present inventors have further examined propane-1,3-dione derivatives and confirmed as a result that a propane-1,3-dione having 2-(1,3-dihydro-2H-benzimidazol-2-ylidene), or a compound which has benzene or thiophene ring substituted with a group derived from 1-hydroxymethyl, shows excellent availability, in addition to its excellent GnRH receptor antagonism, thereby accomplishing the invention. Since the compound of the invention shows excellent availability, in addition to its strong GnRH receptor antagonism, it can be expected that it exerts superior drug effect in the living body, and it is useful for the treatment of sex hormone dependent diseases such as prostate cancer, breast cancer, endometriosis, uterine leiomyoma, benign prostatic hypertrophy and the like. In addition, since the compound of the invention is excellent in metabolic stability in human and also is less in drug interaction, it has more desirable properties as a medicament to be used for the aforementioned diseases.