We experienced successful treatment of postoperative severe pneumonia of Methicillin-resistant Staphylococcus aureus (MRSA) with combination therapy of Arbekacin (ABK) and Fosfomycin (FOM) in three lung cancer patients. Case 1 was a advanced age of seventy-nine man who had had right upper lobectomy. Case 2 was a 61-year-old man who had had left lower lobectomy and extended bilateral mediastinal lymph-node dissection through the median sternotomy. And case 3 was a 59-year-old man who had suffered from pulmonary embolism after right pneumonectomy and partial resection of left atrium and superior vena cava. All cases were immuno-compromised patients and super-infected with Gram-negative rods, and Pseudomonas aeruginosa in case 1 and case 3. Clinical symptoms were improved after the start of administration of ABK and FOM inspite of ineffectiveness of prior treatment with other antibiotics. We added staggered chemotherapy of Sulbactam/Cefoperazone (SBT/CPZ) and Ceftazidime (CAZ) for case 1 and case 3 respectively. Thus, the combination therapy of ABK and FOM might be useful for severe pneumonia of MRSA in the immunocompromised patients, and the combined staggered chemotherapy of beta-lactum agents and above would be the first choice in the treatment for the case involving Pseudomonas aeruginosa.