掌管天地人三界的神祇。俗稱三界公，指天官、地官、水官，最早出現在張道陵所創之天師道，天師道是道教正一派的前身，三官大帝在天師道的首過治病儀中，是人們懺悔上書的對象，懺悔者需手寫告罪文書上告天、地、水三官，分別置入山上、地下、水中，此儀式稱為即三官手書。三官本於上三天玄、元、始之氣，是東漢道教因應時代提出的宇宙觀，本代表當時道教的最高神，後來形成職掌天、地、水之三官。民間固然也有三界公即是堯、舜、禹的說法，應是把漢人宇宙觀中抽象的天、地、人三界人格化的結果。
三官大帝也和三元日有關。至少在唐朝之前，人們已經認為三元之日是三官裁量人們的功德過失之日，上元是天官校計人們功德之日，上元是天官校計日，中元屬地官，下元則屬水官。另有一說是農曆正月15日上元是天官的生日，7月15日中元是地官的生日，10月15日下元是水官的生日。三官大帝經歷魏、晉、南北朝的演變，至唐代將三元節祭拜三官定型化，以此表示漢人宇宙觀有天、地、人三界的觀念，因為人存在於天、地之間，而漢人又是農業民族，以稻米為生，水稻的種植與水有密切的關係，因此以水官象徵人界。三元節這三個日子是臺灣民俗的重要節日，上元節是元宵節，俗例年初要向上天祈福，元宵是新春祈福活動的最後一天，也是最高潮的一天。中元節需普度好兄弟，下元做年尾戲或平安戲向三界公感恩人界的豐收。
台灣之三界公廟不多，多以三界公廟、三元宮、三官大帝廟為名。數量約莫在十多座至二十座之間。但是三界公在臺灣民間信仰有其特殊地位，信仰非常普遍，往昔三合院式的民宅正廳皆垂吊有「三界公爐」，有時會以三界公爐懸吊鐵鍊的耳朵來區分族群，三耳的是漳州人，四耳的是泉州人。庄社祭祀三界公的情形也很普遍，有些地方早期有「三界公壇」簡稱為「公爐」，許多「公爐」、「公厝」即是以三界公為主神。往昔也有庄社有「三界公會」，以頭家、爐主的方式祭祀三界公，即使沒有「三界公壇」，也會在土地公廟或村廟，或是在值年爐主的家中祭祀三界公。
關鍵詞：三官大帝、三界公爐、三界公會、三界公、公壇、天地人、宇宙觀
參考書目
田金昌。2005。〈北臺灣客家人的三官大帝信仰初探〉。《新竹文獻》，18：92-106。
呂理政。1990。《天、人、社會：試論中國傳統的宇宙認知模型》。臺北：中研院民族所
林美容。1990。〈族群關係與文化分立〉。《中央研究院民族學研究所集刊 》，69：93-106。（http://www.sinica.edu.tw/ioe/chinese/staff/r2602/etb069-005.pdf）
推薦書目
馬永金。1995。《三官大帝傳》。臺中：金玉堂。
黃榮洛。1996。〈臺灣客家人和三官大帝廟〉。《客家雜誌》，75：8-61。
黎志添。2002。〈天地水三官信仰與早期天師道治病解罪儀式〉。《臺灣宗教研究》，2（1）：1-30。
Sanguan dadi, Emperors of the Three Offices, are three highest gods who administrate the world in Chinese popular religion. Sanguan dadi are Tian guan (天官), Di guan(地官), and Shui guan (水官). Tian (天), di (地) and shui (水) denote the heaven, earth and water in Chinese individually. Guan means office. Sanguan dadi are also called Sanjie gong (三界公). The early record about them is a religious healing ritual named Sanguan shoushu (三官手書). Sanguan dadi are the gods whom a Daoist confesses ones own sins to in Sanguan shoushu. Sanguan shoushu is a ritual created by Daoists in Tianshi dao (天師道), a proto Daoist sect. If a devotee confesses ones own sins by way of Sanguan shoushu, one should write three confessional documents to Sanguan dadi and place one of them on a mountain, sink one in the river, and bury one in the earth. Sanguan, Emperors of the Three Offices, were the gods revealed by Daoists in Eastern Han dynasty to respond a new cosmology. They were original representing the three primal qi (氣). They became three offices later.
By Tang dynasty, Sanguan dadi were linked to Sanyuan ri (三元日), three days of the three Primary. Sanyuan ri are the fifteenth by January, July, and October in Chinese lunar calendar. Daoists believe that these three days are the days of judgement belonged to Sanguan dadi separately. January the fifteenth is the day of Tian quan. July the fifteenth is the day of Di guan and October the fifteenth is the day of Shui quan. Another version is the three days are the birthdays of Sanguan dadi individually. People worshiping to Sanguan dadi in Sanyuan ri became a custom by Tang daynsty. In Taiwan, Sanyuan ri are three important days in popular religion. January the fifteenth is called Yuanxiao jie (元宵節). It is the last day of Spring Festival (春節) and is celebrated as the Lantern Festival. Zhongyuan jie (中元節), the fifteenth day of the seventh month in the lunar calendar, is the day that people take on a ritual to transform and offer food to the deceased. Xiayuan ri(下元日), the fifteenth day of the tenth month in the lunar calendar is the day that many temples invite traditional troupe to perform plays as the offering to the gods.
According to the statics, it is estimated about dozen to twenty-odd temples dedicated to Sanguan dadi in Taiwan. Most of them are named Sanjie gong temple (三界公廟), Sanyuan temple (三元宮) or Sanguan dadi temple (三官大帝廟). Though the number is few, the belief on Sanguan dadi is very popular. There are many compound houses hung a censer dedicated to Sanguan dadi. The style of censer hung in the hall of traditional compound building dedicated to Sanguan dadi is according to the identity of devotees. The devotees of Zhangzhou (漳州) use the censer with three rings. The censer with four rings belongs to the devotees of Quanzhou (泉州). Some villages also organize a gropus and place a censer dedicated to Sanguan dadi. The heads of group take the duty of worship to Sanguan dadi in turn.
Keywords: Association for Lords of Three spheres, Communal Shrine, Three spheres : Heaven, Earth, and Human, Cosmology