Production method of an optically active morpholine compound represented by the formula 10, or a compound represented by the formula 55, which includes the following steps: or wherein each symbol is as defined in the specification. An optically active 2-aryl-substituted morpholine compound and 3-oxo-3-(pyrimidin-4-yl)propionate, which are important as starting materials for synthesizing 2-(2-arylmorpholin-4-yl)-1-methyl-1H-[4,4′]bipyrimidinyl-6-one having a tau protein kinase 1 inhibitory activity and useful as a therapeutic drug for Alzheimer's disease and the like, can be produced in a high yield by an industrially advantageous method.