Diagnostic image features of the omental cyst remain to be fully understood because of its rarity. We present here a case of omental cyst in a 29-year-old man involving several diagnostic image features. Contrasted computed tomography showed thin ring-like enhancement, and angiography revealed the feeding arteries that branched from the right gastroepiploic artery. The cyst was excised surgically, and the final pathological diagnosis was an omental pseudocyst.