Abstract: A method for collecting a heavy rare earth element from a heavy rare earth element-containing molten salt electrolysis residue and recycling the heavy rare earth element, the method includes: a step of mixing coarse particles of the molten salt electrolysis residue with a fluorinating material followed by firing, to fluorinate the coarse particles of the molten salt electrolysis residue; a step of pulverizing the coarse particles of the fluorinated molten salt electrolysis residue to obtain a powder of the molten salt electrolysis residue; and a step of mixing the powder of the molten salt electrolysis residue with R, an R-M alloy, or an R-M-B alloy (wherein R is one or more types of rare earth elements selected from the group consisting of Y, La, Ce, Nd, Pr, Sm, Gd, Dy, Tb, and Ho, M is a transition metal such as Fe or Co, and B is boron), heating and melting the mixture, separating a molten alloy from slag, and selectively extracting the heavy rare earth element into the molten alloy.