The present invention relates to a reagent for determining the absolute configuration of a chiral compound containing as an active ingredient a metalloporphyrin dimer, wherein the metalloporphyrin dimer has an alkaline-earth metal ion as a central metal and has a carbon chain-crosslinked structure in which at least one of the two porphyrin rings has a substituent bulkier than methyl at least one of the second carbon atoms from a carbon atom bonded to the crosslinking carbon chain along the outer periphery of the porphyrin ring and a method for determining the absolute configuration of an asymmetric carbon atom of the chiral compound using the reagent.