Strong magnetization was observed in a cyclically deformed Fe-35 at.% Al alloy by introduction of a high density of antiphase-boundary tubes. In order to introduce a large plastic deformation without changing the specimen dimension, compressive deformation was given repeatedly along mutually orthogonal stress axes under a constraint imposed across the stress axes. Clear evidence was obtained in attributing the major origin of the large magnetization to the production of a high density of APB tubes. The contribution of the APB tubes (...) to the strong magnetization and to the work hardening is discussed on the basis of quantitative analyses of the microstructures introduced by cyclic deformation. (shrink)