An abnormality detection apparatus includes: a state observation section that observes tool weight data on weights of tools attached to a tool exchange device, tool balance data on balances of the tools, and tool exchange state data on a state during exchange of the tools; a tool exchange state data storage section that stores the tool weight data, the tool balance data, and the tool exchange state data in association with each other; and a determination result output section that detects an abnormality in the exchange of the tools based on the tool weight data, the tool balance data, and the tool exchange state data observed by the state observation section during the exchange of the tools in the processing machine and the data stored in the tool exchange state data storage section.