[Problem] To make it possible to perform desulfurization of molten pig iron efficiently and in a short time. [Solution] A molten pig iron processing method comprising: steps for scraping out pre-processing slag from a molten pig iron ladle 9 into a slag chute 4 and for scraping out post-processing slag from a recycling pit 6 into a recycling chute 7; a step for moving the slag chute 4 near a pre-processing slag pit 5 and the recycling chute 7 near the molten pig iron ladle 9; steps for discarding the pre-processing slag from the slag chute 4 into the pre-processing slag pit 5 and for depositing the post-processing slag from the recycling chute 7 into the molten pig iron ladle 9; a step for desulfurization of the molten pig iron in the molten pig iron ladle 9; a step for moving the slag chute 4 near the molten pig iron ladle 9 and the recycling chute 7 near the recycling pit 6 during the desulfurization step; a step for scraping out the post-processing slag from the molten pig iron ladle 9 into the slag chute 4; and a step for depositing the post-processing slag from the slag chute 4 into the recycling pit 6.