The ‘keX(可X)’ type adjective is very deeply related to the diachronic transition process of ‘ke(可)’. ‘ke(可)’ comes to the stage of changing from the verb to the auxiliary verb, followed by a syllable verb and adjective morpheme. After taking the work ‘於’, it accompanies a syllable noun morpheme. The ‘keX (可X)’ type adjective started from this syntactic structure. And as this structure becomes customary, ‘ke(可)’ would gradually function similar to a kind of prefix constituting ‘keX(可X)’ type adjective. One noticeable point is that the derivation of the ‘keX(可X)’ type adjective is still underway and will possibly continue in the future. From the functional aspect of the adjective, it can be seen that the ‘keX(可X)’ type adjective has a more adjective typical adjectives with higher commercialization and customization. On the other hand, adjectives with a relatively low degree of commercialization and customization tend to exhibit such characteristics passively.