本研究以《現代日本語書き言葉均衡コーパス（BCCWJ）》為語料，抽取1200例「二字漢語＋二字漢語」形式的臨時性四字漢語，專注於其名詞用法，從語義關係與統語關係兩方面進行分析。語義分類顯示，「主題－行為型」「対象－施策型」「機関－制度型」最為頻繁，反映出此類表現與社會制度、行政活動密切相關。統語分類則涵蓋八大類，其中「主語＋述語型」「目的語＋述語型」在資訊凝縮上具有核心作用，而「修飾＋被修飾型」「並列型」則突顯邏輯與語義的多樣性。研究結果表明，臨時性四字漢語不僅是語彙結合，更承載了句法與語義的壓縮功能，成為現代日語重要的表達資源。今後將深入探討助詞共起、品詞轉換與語序制約，並探索其在日語教育及自然語言處理上的應用可能性。

This study investigates temporary four-character compounds (yojikango) in Modern Japanese, focusing on their nominal usage. Based on the Balanced Corpus of Contemporary Written Japanese (BCCWJ), 1,200 examples of “two-character compound + two-character compound” structures were extracted and analyzed from semantic and syntactic perspectives. Semantic classification reveals that “theme –action,” “object–policy,” and “institution–system” types are most frequent, indicating their close relation to social institutions and administrative activities. Syntactic classification covers eight major types, with “subject–predicate” and “object–predicate” structures playing central roles in information condensation, while “modifier–modified” and “coordinate” structures highlight logical and semantic diversity. The findings demonstrate that temporary four-character compounds function not merely as lexical combinations but as compressed syntactic-semantic units, serving as essential resources in modern Japanese expression. Future research will examine particle co -occurrence, part-of-speech shifts, and word order constraints, with potential applications in Japanese language education and natural language processing.