This method is for producing a transition metal complex represented by formula (2), the method comprising reacting a compound containing a transition metal selected from V, Cr, Mo, W, Fe, Ru, Co, Rh, Ni, Pd, and Pt with an isocyanide compound represented by formula (1) in the presence of an alkali metal supported by a solid substance which is insoluble in an organic solvent. This production method can be used to easily and efficiently produce a transition metal complex that includes a predetermined transition metal having an oxidation number of 0 and that has the same or different isocyanide compounds, without using a compound harmful to the human body. (1): (CN)x—R1 {R1 represents a mono- to tri-valent organic group having 1-30 carbon atoms, and x represents an integer of 1-3}. (2): M1a(L)b {M1 represents V, Cr, Mo, W, Fe, Ru, Co, Rh, Ni, Pd, or Pt, and is a zero-valent transition metal, L represents an isocyanide compound represented by formula (1), M1 and L may be the same or different from each other, “a” represents an integer of 1-8, and b represents an integer of 2-12}.