A metal component absorption enhancer which enhances the absorption of at least one metal component selected from the elements belonging to groups 2 to 12 in the third to fourth periods when a plant grows. The metal component absorption enhancer contains 5-aminolevulinic acid or a derivative thereof represented by the following general formula (1), or a salt thereof as an active ingredient: R2R1NCH2COCH2CH2COR3  (1) wherein R1 and R2 each independently represents a hydrogen atom, an alkyl group, an acyl group, an alkoxycarbonyl group, an aryl group, or an aralkyl group; R3 represents a hydroxyl group, an alkoxy group, an acyloxy group, an alkoxycarbonyloxy group, an aryloxy group, an aralkyloxy group, or an amino group, and is used for performing a treatment with 0.001 to 20 ppm of the 5-aminolevulinic acid, the derivative thereof, or the salt thereof per each time.