The particle -ja, which corresponds to -wa in Japanese, is widely used in Ryukyuan languages in general. Previous studies on this particle have mostly focused on its morphological aspects such as allomorphy and combinatory possibilities with other particles, leaving aside other aspects such as grammatical function and meaning. Characterisation of -ja in Ryukyuan as compared with -wa in Japanese has also been left open for future research. Focusing on Tarama (Southern Ryukyuan), this study aims to describe basic construction types in which -ja occurs, and their structures and functions. I will show that subject NPs marked with -ja in nominal and adjectival predicates denote what I call 'topic of judgement', whereas those in verbal predicates denote what I call 'topic of relevance'. Other -ja constructions include existential predicates with the existential aL, negative constructions, and comparative constructions.