Job advertisements are featured by the use of simple sentences and complex nominal groups that can cause possible different perceptions between one reader and another. Therefore, carefulness in understanding job advertisements is a matter of urgency. One characteristic of a complex nominal group used in job advertisements is the post-nominal modifier, which functions to give clear meaning to the nominal group itself. This study examines the use of post-nominal modifiers and aims to identify the constituent elements as well as the types of circumstantial elements in post-nominal modifiers contained in English language job advertisements. The job advertisements were obtained from one of the largest job market websites in Indonesia; jobstreet.com. This study used a descriptive qualitative method through the Systemic Functional Linguistics (SFL) approach. The results found that all post-nominal modifiers consist of prepositional phrases, with the preposition "in" (60%), "of" (14.3%), "with" (11.4%), "as" (4.3%), and "at", "for", and "to" (1.4%). Meanwhile, the types of circumstantial elements found in the post-nominal modifier are the type of matter (80%), mannermeans category (7.1%), accompaniment-comitative category (4.3%), location-place category (4.3%), and the role-guise category (4.3%). The result of this study is significant to the teaching and learning of text analysis and English grammar, especially in the discussion of noun groups or prepositional phrases.