Partition cells are cholinergic interneurons that are located in lamina VII of the spinal cord. Medially located partition cells provide inputs, known as C-terminals, to motor neurons and modulate motor activity. Partition cells are categorized into three groups (medial, intermediate, and lateral groups) according to their distance from the central canal. However, morphological characteristics of three groups of partition cells remain obscure. In order to determine the feature of partition cells, we performed neuronal tracing using the combination of adenovirus vectors and Cre/lox-mediated recombination. Each group of partition cells showed different dendritic orientation and dendritic fields. Medial partition cells had ventrally oriented dendrites that extended mainly in the medial part of lamina VII. Intermediate partition cells radiated dendrites to horizontal orientation and their dendritic trees covered mainly the lateral part of lamina VII. Lateral partition cells showed no preference in their dendritic orientation. These dendritic features of partition cells indicated that each group might receive different inputs. In addition, we revealed that C-terminals originated not only from medial partition cells but also from intermediate/lateral partition cells.