In this paper, I considered the significance of pottery inscribed in ink with the character sen (専). There are very few examples of such pottery and sen is not believed to have been a commonly used character in ancient society. Sen can be written with a single character or with two or more characters, and in the latter case, the word sentō (専當) is found. The word sentō has the meaning of taking responsibility for a specific task and is also used as the name of a position in the imperial court and at shrines and temples. Especially in the ancient period, it is thought to have been related to duties concerning taxation, duties surrounding the land of temples and shrines, and the duties of manor administrators. The meaning of sentō can be confirmed from examples of its use in historical documents. Based on an analysis of the sites where pottery bearing ink inscriptions of sentō and sen has been unearthed, I suggested that even when the single character sen was used, it had the meaning of sentō.