This article describes the electron-microscopic observations of an FeBSi 2 ribbon which was fabricated by a spin-casting technique and then annealed for 3.6ks at 1053K. The electron diffraction spots split along a [111] * reciprocal direction in rodlike crystal grains with the FeSi 2 structure. The splitting was associated with a long period structure, which was found to be constructed of stacking faults on (111) planes by a lattice image observed at the electron incidence of [3 12] zone axis and by its simulation based on the matrix method of dynamical diffraction. Spacings between the stacking faults ranged from 0.3 to 2nm.