To gain a semi-solid alloy the electromagnetic stirring by an induction motor of 3 phase and 2-poles was used. And it was also observed that the change of primary particle size, distribution and degree of sphericity by addition of a refiner, Al5Ti1B. The effect of refiner on the distribution and dimensions of primary particles prior to that electromagnetic refining on those was examined. In case of electromagnetic stirring with the refiner Al5Ti1B, the average size of primary solid particles increased as the fraction of solid increased. However it decreased as the amount of Al5Ti1B addition increased to 0.5% and then it was increased again as the addition amount of Al5Ti1B increased above 1.0%. The average size of primary solid particles was 31㎛ in case of melt temperature 600℃ when the fraction of solid was 0.3, input voltage 140V, cooling rate 2.5℃/s, and 0.5% Al5Ti1B. To use the electromagnetic stirring with the addition of a refiner was able to obtain more small primary solid particles than to use the electromagnetic stirring only.