A 65-year-old woman with suspected ascites-associated abdominal distention had elevated CA125 levels. Contrast-enhanced computed tomography to search for the cause of the ascites showed bilateral pleural effusions, ascites, and an ovarian tumor. On magnetic resonance imaging the tumor exhibited a lobulated structure and markedly low signal intensity on both T1- and T2-weighted imaging, with no restrictions on diffusion-weighted images. Progressive enhancement was observed at tumor margins. Meigs syndrome due to fibroma was suspected, and total hysterectomy, bilateral salpingo-oophorectomy, and partial omentectomy were performed. Postoperatively, the pleural effusion and ascites resolved promptly without specific treatment. On pathological examination, the ovarian tumor was diagnosed as a benign Brenner tumor with scattered nests of transitional epithelium within a large amount of stroma. Based on the clinical course, the patient was diagnosed with pseudo-Meigs' syndrome due to a Brenner tumor.