The present invention provides a novel 6,7-dihydroimidazo[2,1-b][1,3]oxazine compound that has excellent bactericidal action against tubercle bacilli, multidrug-resistant tubercle bacilli, and atypical acid-fast bacilli. Specifically, the present invention provides a compound represented by Formula (1):or a salt thereof,wherein R1 represents tetrahydroisoquinolyl, tetrahydroquinolyl, tetrahydrobenzoazepinyl, benzoxazolyl, benzothiazolyl, indolyl, isoindolinyl, naphthyl, quinolyl, phenyl, biphenylyl, or pyridyl, these groups being optionally substituted, the phenyl, biphenylyl, and pyridyl represented by R1 each being substituted directly or via a linker with at least one group selected from the group consisting of tetrahydropyridyl, diazepanyl, diazabicycloheptanyl, tetrahydrotriazolopyrazinyl, tetrahydroimidazopyrazinyl, azabicyclooctanyl, oxazolyl, piperazinyl, piperidyl, thiazolyl, and the like, each of these groups being optionally substituted and R2 represents hydrogen or lower alkyl. The present invention further provides a pharmaceutical composition containing the above.
