Clinical Trial to Assess the Efficacy and Safety of YYD601 in the Treatment of Esophageal Reflux Disease (ERD)

* A man or woman over 20 years old less than 70 years old.

* A man or woman who has experienced symptom (heartburn and acid regurgitation) within 7 days before Visit 1, meet below 1) or 2) criteria, who has been made diagnosis as Erosive esophagitis(LA grade A~D) measured through the endoscopy which is carried out within (-2W±D2)

* A man or woman who has a full understanding of this clinical trial through the detailed explanation, agree in writing to participate in this trial.

* Who has hyper sensitivity reaction about other drugs, ingredients, components of investigator product or compound of benzimidazole.

* Who has NERD

* Who get a diagnosis as a IBS within the last 3 months.

* Who have taken gastric acid secretion inhibitors including PPIs within 2 weeks before the endoscopy.

* Who have taken drugs about reflux esophagitis (H₂-receptor inhibitor (H2RA) Prostaglandin(PG), Antacid, Prokinetic acid etc.) above 2 times as an usual dose. (* refer to the Concomitant medication in text.)

* Who has been experienced the disease affecting the esophagus(Eosinophilic esophagitis, esophageal varices, cirrhosis, Virus or Fungal infection, Esophageal stricture, primary esophageal motility disorder and gastrointestinal bleeding). Or who has a history of radio therapeutics, freeze treatment about the esophagus.

* Who has clinically significant abnormal result of ECG.

* Abnormal result of Major arrhythmia, Multifocal PVS, 2 AV-blcok etc.

* Who has the Schatzki near the LES(lower esophageal sphincter) except the Barret's esophagus.