Derivatives of 2-substituted-cycloheptoimidazole are disclosed, which are represented by the following formula: ##STR1## wherein R is a hydrogen atom, a lower-alkyl, acetyl, lower-alkylaminoalkyl or ethylenedioxyethyl group. A represents a phenyl, pyridyl, benzimidazolyl, imidazolyl, thiazolyl, thiadiazolyl, oxazolyl or isoxazolyl group; each of which optionally possesses one substituent or more and m is 0 or 1, and n is 1 or 2. These compounds are useful as anti-ulcerative agents.