Jacques Lacan and Stephen Greenblatt, in their criticisms of Hamlet, "Desire and the Interpretation of Desire in Hamlet" and Hamlet in Purgatory, both deal with the question of "mourning" seriously though they approach it with different interests and perspectives. Lacan's analysis of Hamlet, however, has an aspect that makes readers who are unfamiliar with Lacanian theory, feel difficult to understand what Lacan intends because of his some specific psychoanalytic terms. On the other hand, Greenblatt's telling of Hamlet with his emphasis on Hamlet's "mourning" provides readers with various historical and social resources to get Renaissance context of mourning but is lacking in satisfying readers literary curiosity, for instance, into Hamlet's multi-layered subjectivity. Thus, this paper interrogates into a connection between "mourning" and Hamlet's internally split subjectivity. This crucial connection is, however, first investigated not by Lacan's analysis above but by the examination of Sigmund Freud's "Mourning and Melancholia." But this first step to open a more accessible reading of Hamlet's mourning through Freud's "Mourning" leads us to reason what Lacan means to say; in this sense, it manifests a certain "Lacan's return to Freud" as is often called. Furthermore, this paper shows an essential relationship called "implication" between literature and psychoanalysis, here, Shakespeare's Hamlet and psychoanalysis via the subject of "mourning". Thus, this paper plays a trio between Hamlet, Freud, and Lacan. Freud distinguishes mourning and melancholy by explicating mourning as taking place in the conscious while considering melancholy as emerging in the unconscious realm. But, in Hamlet, this division between mourning and melancholy, conditioned by the boundary between the conscious and the unconscious, is unsettled. Rather, mourning and melancholy, in Hamlet, aggravates each other's extent: mourning gives rise to melancholy, and melancholy deepens mourning in a profound way. One of the most obvious problems in Hamlet is Hamlet's consistent hesitancy to revenge related with the question of "insufficient mourning" which actually motivates both Hamlet and Laertes to revenge. Laertes decides, plans, and performs a revenge in a play whereas Hamlet does not despite his ceaseless declarations of revenge. Hamlet's this reluctancy before his father's command of revenge explains that Hamlet's feeling of loss caused by his father's sudden death and the following his mother's remarriage to his step-father, Claudius, is of the unconscious not of the conscious one. This loss that makes Hamlet disabled in revenge is much related with the loss Freud elucidates as the cause of melancholy; in melancholy, she is aware that she has experienced a kind of loss, but she cannot see what has been lost, to be more exact, she does not know what she has really lost in that loss. Hamlet's unconscious loss certainly has to do with his recognition of his father's sin which was strongly indicated in his mother's sexuality and his father's own confession. Next, the father's sin is internalized into Hamlet's own ego. This makes Hamlet split from himself, which results in the self-reproaches or the impoverishment of the ego, as indicated in Freud's second explication of mourning and melancholy. In this process, the relation between the ego and the loved object is changed into the conflict between the ego and its another ego. In Hamlet, Hamlet's encounter with his father's ghost intensifies Hamlet's own awareness of his own guilt. From the moment he faces his father's ghost, he can be never free from this guilty feeling; he feels guilty at the level of existence. The only moment Hamlet can be released from it is when he dies. Hamlet's death completed by the annihilation of himself and his ideal-ego reflected in his partner of a duel, Laertes, is the moment of his entrance into the symbolic order as Lacan says.