A 58-year-old woman was referred to our hospital for Cushingoid features and diagnosed as adrenal Cushing\'s syndrome due to a right adrenocortical mass (60 × 55 mm). The mass was composed of three different tumors; the first one was homogeneously lipid-poor neoplasm measuring 20 × 13 mm located at the most dorsal region, the second one was heterogeneous and lipid-rich tumor containing multiple foci of calcification measuring 50 × 32 mm located at the central region, and the last one was heterogeneous harboring dilated and tortuous vessels and lipid-poor one measuring 35 × 18 mm at the most ventral region of the adrenal gland. A right adrenalectomy was subsequently performed by open surgery. Macroscopic and microscopic analyses revealed that all three tumors were adrenocortical adenomas; the first one represents a pigmented adrenocortical adenoma, the second one adrenocortical adenoma associated with degeneration, and the third one adrenocortical adenoma harboring extensive degeneration. Immunohistochemical analysis of the steroidogenic enzymes also revealed that all of the tumors had the capacity of synthesizing cortisol. This is a very rare case of Cushing\'s syndrome caused by multiple adrenocortical adenomas including a pigmented adenoma. Immunohistochemical analysis of steroidogenic enzymes contributed to understanding of steroidogenesis in each of these three different adrenocortical adenomas in this case.