日本語の略語の中に「コン」を複合語の後項にもつ例がとりわけ多く、例えば、「エアコン」「パソコン」「マザコン」「ミスコン」などが挙げられる。が、この生産性をもつ後項要素「-コン」は実は同じ意味ではなく、同音異義の関係を有すると思われる。本稿ではこの複合略語の後項に位置する「-コン」について、まず、意味の側面から「-コン」の元語基は何なのかを確認し、次に、造語カや造語法、略語の略し方、結合相手といった語構成の観点から「-コン」の語構成的特徴や形態素としての位置付け、本質などの造語性を究明することにした。本稿の考察により、「-コン」の意味について、「コンサート」をはじめ、「コンピューター」「コンパ」などの34個の元語基を確認できた。次に、「-コン」の語構成的特徴に基づき、(前後略の短縮法による)[2音節の外来語要素+コン]という「〜コン」複合略語の典型的な造語パターンも解明した。最後に、「-コン」を宮島(1972=1994)の無意味形態素及び「ロケ」「レジ」といった外来語省略語基と比較しながら、「-コン」の本質を分析し、「-コン」は短縮形拘束語基という形態素としての位置付けを論じた。|Many of the rear constituents of abbreviation compound words in Japanese are the loanword morpheme"-CON", such as "EAKON", "PASOKON", "MAZAKON", "MISUKON" and so on. However, all of the abbreviation compound words with rear constituent "-CON" mentioned above actually don't mean the same. They are homophones. The study will clarify the meaning of the compound abbreviation "-CON" which is the rear constituent from the semantic order first. Then, investigating the essence of Japanese morpheme "-CON" from the viewpoint of the word formation rules, word formation ability, the rule of abbreviation and the collocations to discuss the feature of the word formation of "-CON" being the Japanese morpheme. The study confirmed that there are 34 original bases of the homonym of "-CON" including "KONSATO", "KONPYUTA" and "KONPA". In addition, according to the feature of the word formation of "-CON", we could sort out that the most classical word formation pattern which includes abbreviation rear constituent "-CON" is (abbreviations by omitting part of the front and rear constituents) [loanword morpheme with two syllables+ CON]. And last, analyze the essence of "-CON" and discuss its position being a part of the abbreviation of bound morpheme through the comparative analysis of "Unsemantic Morpheme" and the loanword abbreviation base "ROKE" and "REJI" by Miyajima (1972=1994)