  The supernova yields of r-process elements are obtained as a function of the
mass of their progenitor stars from the abundance patterns of extremely
metal-poor stars on the left-side [Ba/Mg]-[Mg/H] boundary with a procedure
proposed by Tsujimoto and Shigeyama. The ejected masses of r-process elements
associated with stars of progenitor mass $M_{ms}\leq18M_{\odot}$ are infertile
sources and the SNe II with 20$M_{\odot}\leq M_{ms}\leq 40M_{\odot}$are the
dominant source of r-process nucleosynthesis in the Galaxy. The ratio of these
stars 20$M_{\odot}\leq M_{ms}\leq40M_{\odot}$ with compared to the all massive
stars is about $\sim$18%. In this paper, we present a simple model that
describes a star's [r/Fe] in terms of the nucleosynthesis yields of r-process
elements and the number of SN II explosions. Combined the r-process yields
obtained by our procedure with the scatter model of the Galactic halo, the
observed abundance patterns of the metal-poor stars can be well reproduced
