本文建構一垂直產品差異性的寡佔模型，探討擁有品質創新的高品質廠商面對多 家低品質廠商競爭下之最適授權契約。研究結果顯示，當市場上存在兩家以上的 低品質廠商時，高品質廠商僅會將其品質創新授權給部分的低品質廠商。當產品 品質差異較小（大）時，固定權利金授權下高品質廠商的總利潤將會高（低）於單 位權利金授權。此外，我們也發現固定權利金授權下的社會福利水準有可能低於 單位權利金授權下的水準。這些結果與文獻中成本下降之最適授權契約相比，有 很大的不同。如果授權廠商採兩部訂價法之授權契約，依產品品質差異的程度大 小，其最適授權契約可能爲純粹單位權利金、正的單位權利金加上正的固定權利 金或純粹固定權利金。值得一提的是，即使在被授權廠商受限於吸收能力而無法 將其產品品質提升至授權之品質水準，以上這些結果仍然成立。

This paper investigates the optimal licensing contract for product innovation in a vertically differentiated oligopoly in which a highquality firm competes with other low-quality firms. We find that the high-quality firm will never license its technology to all the lowquality firms if there are more than two low-quality firms, which is a result that has never been documented in the literature. We also show that fixed-fee licensing is more profitable for the licensor, if the technology gap is small, which is a result opposite to that in the cost-reducing licensing literature. We further show that under certain circumstances, fixed-fee licensing is less socially desirable than royalty licensing. Finally, if the licensor firm adopts a two-part tariff contract, then the optimal contract may consist of a pure royalty, a positive royalty and a positive fixed fee, or a pure fixed fee, varying with the technology gap between the two types of firms. These results hold even if the licensees are subject to capacity constraints and cannot raise their quality to the leucl of then of the licensor via licensing.