There is provided a T-type calcium channel blocker that is a compound of formula (1), a pharmaceutically acceptable salt thereof or a solvate thereof. wherein Ar1 is phenyl group, pyridyl group, furyl group or 2,1,3-benzoxadiazol-4-yl group; nitrogen-containing hetero ring moiety is 1,4-dihydropyridine ring or pyridine ring; Z is a group of formula (2) or CO2R2; Ra and Rb are independently of each other C1-6alkyl group, ANR8R9, CH2OANR8R9, or the like; in case where the nitrogen-containing hetero ring moiety is 1,4-dihydropyridine ring, R1 is C1-6alkyl group, ANR8R9, AN(CH2CH2)2NR8, AN(CH2CH2)2O, AOR8 or benzyl group; R3 is hydrogen atom, C1-20alkyl group, ANR8R9, a group of formula or the like.