Abstract: A compound represented by the following Formula (1) that is effective for the treatment of Paget's disease of bone or hypercalcemia or a medically acceptable solvate thereof; [wherein R1 refers to hydrogen atom, C1-C6 alkyl group optionally substituted with hydrogen group or C1-C6 alkoxy group optionally substituted with hydroxyl group, R2a and R2b refer to hydrogen atom, C1-C10 alkyl group optionally substituted with hydroxyl group, C6-C10 aryl group optionally substituted with hydroxyl group or C7-C12 aralkyl group optionally substituted with a hydroxyl group, or are combined to represent ethylene group. However, a compound in which R1 is a hydrogen atom or a methyl group and R2a and R2b are hydrogen atoms is excluded].

Abstract: A compound represented by the following Formula (1) that is effective for the treatment of Paget's disease of bone or hypercalcemia or a medically acceptable solvate thereof; [wherein R1 refers to hydrogen atom, C1-C6 alkyl group optionally substituted with hydrogen group or C1-C6 alkoxy group optionally substituted with hydroxyl group, R2a and R2b refer to hydrogen atom, C1-C10 alkyl group optionally substituted with hydroxyl group, C6-C10 aryl group optionally substituted with hydroxyl group or C7-C12 aralkyl group optionally substituted with a hydroxyl group, or are combined to represent ethylene group. However, a compound in which R1 is a hydrogen atom or a methyl group and R2a and R2b are hydrogen atoms is excluded].

Abstract: A vitamin D3 derivative expressed by the following general formula (1) [wherein, R is a hydrogen atom or a methyl group, and A is a single bond, —CH2—, —CH?CH—, —CH2—CH?CH—, —CH?CH—CH?CH—, —C?C— or —CH2—C?C—; and a compound in which R is an hydrogen atom, A is —CH2—, the steric configuration at the 1-position is (S)-configuration, and the steric configuration at the 3-position is (R)-configuration is excluded] or a pharmaceutically permissible solvate thereof. The compound can be an effective ingredient of a treating agent for osteoporosis, malignant tumor, psoriasis, hyperparathyroidism, an inflammatory respiratory disease, rheumatoid arthritis, growth onset type diabetes mellitus, hypertension, alopecia, acne, dermatitis, hypercalcemia or Paget's disease of bone.