This study is to investigate the efficacy and safety of M518101 in male and female plaque psoriasis patients with refractory plaques.

Inclusion Criteria:

• Who are able and willing to give signed informed consent
• Who are male or females aged between 18 and 65 years with plaque psoriasis confirmed by the Investigator.
• Who have less than 20% of body surface area (BSA) afflicted with plaques
• Who are neither pregnant nor breast-feeding, nor plan to become pregnant during the study.

Exclusion Criteria:

• Who have a history of allergy to vitamin D3 derivative preparations.
• Who have a history of relevant drug hypersensitivity.
• Who have a history of contact dermatitis induced by a topical medicine.
• Who are pregnant or lactating.
• Who have any renal or hepatic insufficiency, or clinically significant cardiac, renal or hepatic disease.
• Who have clinically relevant history or presence of any disease or surgical history other than psoriasis which is likely to affect the conduct of the study.
• Whose serum calcium levels exceed the upper limit of reference range
• Who have used any investigational medicinal product and/or participated in any clinical study within 24 weeks
• Who have been treated with systemic therapy within 8 weeks
• Who have been treated with biologics within 12 weeks
• Who have been treated with topical therapy during the wash-out and lead-in period.