Idiopathic orbital inflammation (IOI) is a benign, non-infective clinical syndrome characterized by inflammation of the orbit without identifiable local or systemic disorders. Orbital myositis is one classification of IOI and rare in adult male patients. In this article, we report a 41-yearsold male who presented to the eye clinic with swollen, redness, pain, chemosis, and squints on his left eye 2 weeks ago. He had a history of recurrent swollen on his left eyelid and self-treated with methylprednisolone. Visual acuity on right and left eye were 20/25 and 20/30, respectively. The intraocular pressure on the right and left eyes were 18 mmHg and 24 mmHg, respectively. No abnormality in the fundus examination. There was a restriction on the left eye movement to all gaze, and the eye was fixed to the superior temporal direction. Head MRI-scan showed hypertrophy of the lateral and medial rectus muscles on the left eye without any other abnormality in the intracranial cavity. The laboratory examination showed leukocytosis, neutrophilia, lymphopenia, normal thyroid function, low C-Reactive Protein level, and a negative result for the antinuclear antibody test and antids-DNA test. The patient was diagnosed with myositis of idiopathic orbital inflammation and was treated with a high dose of methylprednisolone 1 mg/kg BW/day. Two weeks later, the patient had improvement in his eye movement and the swollen was resolved. The treatment is still ongoing. Finally, we can conclude that comprehensive evaluation and treatment with high-dose corticosteroid results in a better outcome in an adult male patient with myositis IOI