<p>The present invention relates to 7-acylamino-1-carba-3-cephem-4-carboxylic acid and derivatives thereof represented by the following general formula ¢1!: ¢I! (wherein x represents an acyl group, R2 represents hydrogen atom or a protecting group of carboxylic acid and R2 represents hydrogen atom, a lower alkyl group or a lower acyloxy group). These compounds posses excellent antibacterial activities against Gram-positive and Gram-negative bacteria.</p>
