The number of aspiration pneumonia cases has increased in recent times. A definitive diagnosis of aspiration pneumonia is difficult in resource-limited settings where radiological equipment is unavailable. We report the initial diagnosis and subsequent monitoring of aspiration pneumonia in a home medical care setting. An 88-year-old Japanese male presented an acute onset of dyspnea, fever, and productive cough. At home, lung ultrasound displayed pleural effusion along with B-lines and subpleural consolidations. Upon admission, tests revealed increased total leucocyte counts with left-shifted neutrophils, elevated C-reactive protein levels, and positive sputum Gram stain. Chest X-ray imaging and computed tomography (CT) showed bibasilar infiltrates and wall thickening in the left S10 bronchi. The patient was diagnosed with aspiration pneumonia and treated with an antibiotic. After a 10-day hospitalization, lung ultrasound showed some remaining B-lines and disappearance of pleural effusion and subpleural consolidation. Chest X-ray image was normal, and CT revealed pleural abnormality and disappearance of bibasilar infiltrates, consistent with the ultrasound findings. Aspiration pneumonia develops with various clinical signs. However, diagnosis using chest X-ray imaging or CT in resource-limited settings is difficult. Ultrasound might allow physicians to make more accurate judgments, particularly while monitoring aspiration pneumonia following initial diagnosis in resource-limited settings.