客語的「有」字就其語法功能而言可以作動詞、助動詞、及動詞補語用。就其意義上而言，「有」標示著領屬義、強調義、及結果完成義。在這些共時歧異的功能意義背後，實存在著一個核心意義---領有。本論文旨在用語法化理論將客語「有」字之共時分歧用法作一合理之解釋，而提出三個主張：第一、將存在的概念提升至更深層，將之視為領有義的預設。第二、將領有義分析為更基本的基模（source schemas）。第三、利用這些基本的基模來解釋「有」字的各種延伸意義。透過這樣的角度分析客語「有」字句，將可以更合理的解釋「有」的共時歧異現象。 / Hakka Yu 'to own, to possess' has various grammatical functions. It can function as a full-fledged verb, appear in a serial verb construction, serve as an auxiliary, and act as a verbal complement. With the structural complexity, Hakka Yu denotes possession, emphatic assertion and the existence of the resultative state of being. The divergent syntactic behaviors as well as the different functions of Hakka Yu do not share the same surface form by chance. The coincidence suggests that there must be an extant semantic core that links together all the seemingly unrelated functions exhibited by various syntactic structures of Yu. This thesis, aiming at linking the diversity of usage of Yu, claims that the structural divergence of Yu corresponds to the "cline of grammaticality," which synchronically refers to a continuum at one hand of which is a fuller lexical form, and at the opposite end, a reduced grammatical form. Three major claims are therefore advanced to account for the synchronic differences of Hakka Yu.