A substrate processing apparatus can allow palladium atoms to be coupled to a surface of a substrate without performing a silane coupling processing with a silane coupling agent on the substrate. In a substrate processing apparatus 1, a plating unit 4 includes a catalyst solution supply unit 43a and a plating liquid supply unit 45. The catalyst solution supply unit 43a forms a catalyst layer 91 on a surface of a substrate W1 by supplying, onto the substrate W1, a catalyst solution L1 containing a complex of a palladium ion and a monocyclic 5- or 6-membered aromatic or aliphatic heterocyclic compound having one or two nitrogen atoms as a heteroatom. After the catalyst solution L1 is supplied, the plating liquid supply unit 45 forms an electroless plating layer 92 on the catalyst layer 91 formed on a substrate W2 by supplying a plating liquid M1 onto the substrate W2.