A nitride semiconductor device includes a nitride semiconductor layer, channel cells in the nitride semiconductor layer, a source lead region of a second conductivity type in the nitride semiconductor layer, and a source electrode on a side where a first main surface of the nitride semiconductor layer is located. The channel cells each include a well region of a first conductivity type and a source region of the second conductivity type in contact with the well region. The source lead region is connected to the source region. The channel cells extend in a first direction in a planar view from a normal direction of the first main surface, and arranged in a second direction intersecting with the first direction in the planar view. The source electrode is in contact with the source lead region away from a line of the channel cells arranged in the second direction.