Inspector Palmu's Mistake (Finnish: Komisario Palmun erehdys) is a 1940 Finnish detective novel by Mika Waltari. It is the second book of the Inspector Palmu series after the first book, . The protagonist of the book, like his predecessor, is Inspector Frans J. Palmu, who sets out to investigate a rich victim who appears to be died in an accident, but which is revealed to be murder.