A process anomalous state diagnostic device configured to diagnose an anomalous state of a process based on deviation indexes for the magnitude of deviation from a reference that is a normal state of the process includes: a color mapping unit configured to configure a two-dimensional matrix that has a first axis as an axis of a temporal factor including time and that has a second axis as an axis of an item of each deviation index, associate each cell of the matrix with data for an item of the deviation index and the temporal factor, and allocate a color in accordance with the magnitude of the deviation index to each cell of the matrix; and a color map display unit configured to display a color map produced by the color mapping unit.