The scan path circuit

Test data applied serially from a data input terminal 6 is bypassed by a selecting circuit in modules that are not the object of testing and applied to a scan path in modules that are the object of testing. Test data is applied to the control point of the functional module from the scan path, and test result data provided from the observation point of the functional module and fetched by the scan path. The scan path shifts the fetched test result data to provide serially from a data output terminal 7. Each of selecting means 5a-5c operates in response to the selecting data held in the corresponding selecting data holding/propagating circuits 9a-9c. These selecting data holding/propagating circuits 9a-9c shift and hold selecting data applied serially from a data input terminal 10.