This work introduces the theory and practice of differential forms on manifolds and overviews the concept of differentiable manifolds, assuming a minimum of knowledge in linear algebra, calculus, and elementary topology. Chapters cover manifolds, differential forms, the de Rham theorem, Laplacian and harmonic forms, and vector and fiber bundles and characteristic classes. The text includes exercises and answers. First published in Japanese by Iwanami Shoten, Publishers, Tokyo, 1997, 1998.