Palladium plating solution and palladium coating obtained using same

The present invention addresses the problem of providing a palladium plating solution in which occurrence of defective parts such as pin holes on a palladium coating is reduced, and in which heat resistance performance equivalent to that obtained conventionally can be obtained even when a gold plating coating formed on the palladium coating is made thinner. The problem was overcome by: a palladium plating solution containing a soluble palladium salt as a palladium source, and a specific pyridinium compound in which an alkyl group is bonded to a nitrogen atom at the 1-position and one to five of the 2- to 6-positions are substituted with one or more specific substituents selected from the group consisting of an alkyl group, an aryl group, a carboxy group, an alkoxycarbonyl group, a sulfo group, an alkoxy sulfonyl group, an amino group, an alkylamino group, a dialkylamino group, and a cyano group; and a palladium coating obtained by performing palladium plating on a nickel, nickel alloy, copper, or copper alloy