The present invention relates to an adapter (4) for a cable gland, wherein the cable gland (1) comprises a cable gland body (2) having a cable passage and a front connection section (2a). The adapter (4) comprises: a connection body configured to be connected with the connection section (2a); and a plurality of elastic attachment clips (6) projecting from the connection body, wherein the attachment clips are respectively provided with a snap groove (7) configured for engaging with a hole edge of a mounting hole in a detachable manner, so as to enable the adapter to be held in the mounting hole. The present invention also relates to a cable gland unit comprising such an adapter and an integral cable gland unit, thereby achieving a quick and detachable connection of the cable gland unit in the mounting hole.