To provide an electroless palladium plating liquid where, in a three layer plating film terminal of an electroless nickel plating film/ an electroless palladium plating film/a substitution gold plating film, a gold film is formed only by easily treatable substitution gold plating, and, even when electroless nickel-phosphorous having high flexibility is used, which has excellent joining strength in both of wire bonding joining and solder ball joining, and has excellent running properties as well.

The electroless palladium plating liquid at least comprises: a component (a): a palladium salt organic complex; a component (b): sulfide group-containing monocarboxylic acid or the salt thereof; and a component (c): hypophosphorous acid or the salt thereof.