To provide a raw material blending method allowing handling of mass of raw materials to be blended by discrete numerical values corresponding to mass packed in a container, a bag or the like and fractions not reaching the discrete numerical values, in a raw material blending process of blending a plurality of kinds of raw materials.

This raw material blending method includes: parameter setting steps S2, S3 of setting parameters based on a request range of a component ratio and request mass requested in a raw material after the blending, and a component ratio and stock mass of the plurality of kinds of raw materials; and an arithmetic step S4 of obtaining at least one solution satisfying a plurality of constraint expressions each represented by a linear expression by use of the set parameters. The plurality of constraint expressions include: a constraint expression directly or indirectly representing mass of the plurality of kinds of raw materials satisfying the request mass by use of at least one of unit mass wherein the raw materials are packed and fraction mass not satisfying the unit mass; and a constraint expression representing the mass of the plurality of kinds of raw materials satisfying the request range of the component ratio by use of at least one of the unit mass and the fraction mass.