In the nanocrystalline Fe78Si10B12 thin film, a weak dense stripe domain structure is observed. Out-of-plane anisotropy accounts for the observed domain structure. Perpendicular shape anisotropy due to the formation of the island-like configuration by the annealing treatment and magnetocrystalline anisotropy due to the strong alpha-Fe(Si) (110) texture are considered to be the origin of the perpendicular anisotropy. A metastable domain structure, which is the superimposition of the fine dense stripe domain structures onto the in-plane wide basic domains, was also observed in the as-annealed sample. The metastable domain structure turns to a stable single-domain state after magnetization. (c) 2004 Elsevier B.V. All rights reserved.