The double-entry bookkeeping ledgers of the Kaesong merchant Park Young-jin's family for ginseng field (sampo) accounting cover records from 1897 to 1905. Although the sampo associations (dojung) correspond to today's subsidiaries, the Park Young-jin family accounted for each sampo association in a single account. For each sampo association, expenditures were treated as investments and debited to the respective association's account, while all revenues were credited, and these entries were posted to the ledger and the subsidiary book called the gagin hoegyechaek (individual accounting book). Until the year immediately preceding the termination of the sampo, profits were not recognized and profit or loss was not calculated; instead, the debit balance—obtained by subtracting credit amounts from debit amounts—was carried forward as an asset, similar to unrecovered investments. The debit balance was reported on the balance sheet (juhoegye) at the end of each fiscal year. In the year when the sampo association was terminated, profit or loss was calculated by subtracting the debit balance (representing unrecovered investments) from revenues, and the association was liquidated by distributing the results to its members. The sampo association accounting reflects modern management concepts. Because the cost of capital was calculated and added to sampo investments and revenues, the sampo profit corresponds to today's residual income. This record is the world's first and only record that explicitly reflects the cost of capital in accounting. Market prices were applied to internal transfer transactions involving the transplantation of cultivated seedling ginseng to other ginseng fields. Considering that transfer pricing began to be discussed in the West only in the 1950s, one can appreciate how far ahead the Kaesong merchants were in optimal decision-making. The equal recognition of the value of capital contributed by members, specialized cultivation techniques, and management know-how to the sampo association—distributing profits equally and applying a cost of capital lower than the market interest rate—represents a mutually beneficial management approach compared to today's capital-centric management. To diversify the risks associated with sampo management, associations were formed, and various management methods were employed to respond to changes in market conditions. These modern management concepts of Korean Kaesong merchants around the turn of the 20th century represent exemplary evidence of rational economic activity in Korean history.