This is a multiple-dose, double-blind, double-dummy, active-control, parallel-group, multi-center, safety and efficacy study.

Inclusion Criteria:

• Males or females age are ≥20 ,≤80 years.
• Clinical diagnosis of musculoskeletal pain for 4 weeks or longer with non-malignant pain etiology at Visit 1.
• Subject is a current user of NSAIDS or paracetamol and reports a history of insufficient therapeutic benefit in musculoskeletal pain.
• Subjects must record an 'average pain over the last week at study institution' score at primary pain site of ≥ 4 on an 11-point numerical pain rating scale.
• Subjects must be able to understands the study procedures and assessment, and agree to participate in the study by giving written informed consent.

Exclusion Criteria:

• Subjects who have been taking long-acting or short-acting opioid analgesic formulations within the last 4 weeks.
• Subjects who have a current chronic disease(s) or who have a past history and high possibilities to relapse, in addition to their musculoskeletal pain, requiring frequent analgesic therapy.
• Subjects with clinically unstable respiratory disease, dysfunction of the biliary tract, thyroid disease, adrenal cortical insufficiency, prostatic hypertrophy requiring intervention or renal artery stenosis.
• Subject who have a past history of malignant neoplasm including leukemia and lymphoma.
• Subjects with clinically unstable, active or symptomatic heart disease.
• Subjects who have psychiatric disorder, uncontrolled seizures or convulsive disorder and so on.
• Subjects who have a current or past (within 5 years) history of substance or alcohol abuse, or subjects who give a positive result in drug abuse test during the Screening Period.
• Subjects scheduled for therapies within the study period which might effect study assessment.
• Females who are pregnant, lactating or have a possibility of being pregnant.
• Subjects with values > 2 times the upper limit of normal for AST or ALT or total bilirubin at visit 1 or who have severe impaired liver function.
• Subjects with serum creatinine > 2 mg/dL at Visit 1 or who have severe impaired renal function.
• Subjects with serum potassium < 3.5 mEq/L at Visit 1.
• Subjects receiving hypnotics or other central nervous system (CNS) depressants.
• Subjects receiving monoamine oxidase inhibitor (MAOI) within 2 weeks before screening.
• Subjects who have a history of supersensitivity to study drug.
• Known intolerance to and/or lack of effect of tramadol.
• Subjects who participated in a clinical research study within 1 month of study entry.
• Subjects who participated previously in a BTDS study.