Method for decomposing crosslinked rubber

The invention solves the problem of providing a decomposition method of crosslinked rubber capable of improving monomer yield. [Solution] A method for decomposing a crosslinked rubber characterized by comprising: a first decomposition step in which decomposition is performed using a catalyst represented by general formulae (1)-(3) (in the formulae, M is ruthenium, molybdenum or the like, X1, X2, L1, L2 and L3 each independently represent a ligand, R1, R2 and R3 each independently represent hydrogen, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group or the like (here, R1, R2 and R3 each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group or the like); ), L1 and L2, R1 and R2, or L1 and R1 may be bonded to each other to form a ring), and R1 and R2 may be substituted by one or more alkyl groups, halogen, alkoxy groups, or the like. And a second decomposition step in which the decomposition product obtai