「樂」是宋明理學中的一個重要議題，是屬於聖人之學的範疇。而在理學內部，諸家對「樂」的論述並不一致，或以「樂」為聖人之學的目標，或以之為聖人之學的精神境界副產品。本文研究南宋朱子的「樂」論，主要目的在梳理朱子如何繼承北宋諸儒「樂」論，如何進行理論修正。而朱子的這些努力，更重要的是為了回應當時學界趨向簡易的學風，以建立「聖人可學」的典範。朱子「樂」論至少具有以下三方面的價值：（一）「工夫」才是聖人之學的重點，「樂」並不是「聖人之學」的目標。朱子強調，唯有經過工夫歷練，才能成學，至於那「樂底意思」，才會自然地出現。（二）以工夫劃分「樂」的境界：人生命中真實呈顯的「樂」境，不能僅從天理流行處講，而應當從「人」的身、心體踐上得，因此，聖、賢有別，「樂」有不同，端看工夫高下。（三）關於孔、顏、曾、孟四子之「樂」，朱子從工夫上分判之。孔子工夫渾然，已優入聖域；顏子工夫最切實，故最近聖人；曾子只見得天理大意，無工夫體段，只是「狂」而已。至於孟子，工夫雖粗，然而具有剛強卓立之精神，因此學者若欲學聖人，則孟子的入學工夫，還應當放在顏子工夫之前。這是確立了孟子在聖人之學中的重要地位。

As a part of the Learning of a Sage (sheng ren zhi xue), the concept of joy (le) is an important aspect of Song-Ming Neo-Confucianism, and many Neo-Confucian thinkers gave this concept their own interpretations or even presented it as the objective or the result of the Learning of a Sage. This paper considers discourses on the concept of joy by the Southern Song thinker, Zhu Xi, in order to better understand how he both continued the Northern Song line of thought on this concept and clarified its theoretical basis. From this we can see how Zhu Xi was working to correct errors he saw in the direction of contemporary scholarship and to establish a model for how sagehood could be approached through learning.Zhu Xi's concept of joy can be considered from the following three standpoints. 1) Various practices, which are the main point of the Learning of a Sage, rather than joy itself being the goal of this learning. 2) The ways in which practices can divide the realm of joy so that it comes not only from the continuation of the heavenly principle(tien li liu xing), but also from the ways in which an individual embodies that principle. 3) The ways it was presented by Confucius, Yanzi, Zengzi and Mengzi: the practices of Confucius are those of a person already at the level of a sage, those of Yanzi are those of one who is almost a sage, those of Zengzi partake of the great meaning of the principle and so without them one may fall into excess; those of Mengzi may be less refined but they have the spirit of great dedication. Thus Zhu Xi considered that the practices of Mengzi can be a more effective means than those of Zengzi, indicating the relatively high position that Zhu Xi gave to Mengzi's cultivation of joy.