A new analgesic has been developed for T-type calcium channels as therapeutic targets.The present invention provides a T-type calcium channel inhibitor which is a compound represented by formula (1): wherein each of R1 and R2 independently represents —H or —OH; R3 represents —OH; R4 represents —OH or —H; R5 represents a straight or branched alkyl or cycloalkyl-alkyl group having one to ten carbon atoms or a straight or branched alkenyl or cycloalkyl-alkenyl group having two to ten carbon atoms, or a pharmaceutically acceptable salt or solvate thereof. The present invention also provides this T-type calcium channel inhibitor, a medicament containing the T-type calcium channel inhibitor, and a therapeutic or prophylactic agent for a disease having an effective T-type calcium channel inhibitory action.