To provide a methylcarbapenem compound having excellent absorbability through the digestive tracts by oral administration, exhibiting sufficiently high antibacterial property against a wide variety of bacterial strains in the form of an active compound formed in vivo and extremely useful as an agent for the prevention and treatment of infectious diseases (especially bacterial infection diseases).

The compound is a 1-methylcarbapenem compound expressed by general formula I (A is a (substituted) phenyl) or its pharmacologically permissible salt.