颈卵器，又称藏卵器，是某些植物产生及含有卵子或雌配子的多细胞配子体结构或器官。颈卵器有一个长颈和一个膨胀的基部。颈卵器一般长在植物叶状体的表面上。

颈卵器在裸子植物的大配子体中更为缩减且内含在内。而在被子植物门和买麻藤纲中则不使用颈卵器这一词，因为此类植物的大配子体已缩至只有少许个细胞，其中一个分化成卵细胞。

与颈卵器对应的雄性器官为精子器。

An archegonium (pl: archegonia), from the ancient Greek ἀρχή ("beginning") and γόνος ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamete. The corresponding male organ is called the antheridium. The archegonium has a long neck canal or venter and a swollen base. Archegonia are typically located on the surface of the plant thallus, although in the hornworts they are embedded.