Inhomogeneous current systems in bismuth specimens under longitudinal and transverse magnetic fields have been investigated by solving a boundary‐value problem of a rectangular parallelepiped medium to which current electrodes are attached with a finite contact area. The main results are as follows. In a longitudinal field, the current inhomogeneity governed by specimen geometry grows, extending toward the middle part of the specimen, and at the same time the current is condensed around the specimen axis parallel to the magnetic field. This current condensation increases the total resistance and decreases the potential difference measured on a side surface. In a transverse field, conversely, the current inhomogeneity degenerates to be confined in a narrow region near the end surface. Influences of specimen dimensions and electrode contact area are quantitatively discussed.