A 61-year-old man developed shortness of breath 2 weeks prior to a chest computed tomography examination that revealed bilateral pleural effusion with left predominance and bilateral pleural thickening. Cytology showed class II lymphocyte-predominant exudate in the left pleural effusion and transudate in the right pleural effusion. An ultrasound-guided biopsy of the left pleural thickening showed foreign-body giant cells that had phagocytized minute eosinophilic granule-shaped material. A thoracoscopic pleural biopsy revealed deposition of an amorphous material with the spherical shape of eosinophils that was stained positive by Direct Fast Scarlet stain, and pleural amyloidosis was diagnosed. On the basis of urine-positive for Bence-Jones protein and bone marrow aspiration findings, we also diagnosed the patient as having Bence-Jones protein κ-type multiple myeloma. In the present case, shortness of breath due to the pleural effusion accumulation was the initial symptom of the pleural amyloidosis with multiple myeloma.