The purpose of this study is to demonstrate the superiority of efficacy of CJ-12420, once daily (QD), compared to placebo in patients with non-erosive reflux disease at Week 4

This is a double blind, randomized, placebo-controlled, phase 3 study. Subjects will be randomly assigned to one of the three treatment groups (CJ-12420 50 mg or 100 mg or placebo).

All subjects will be asked to take two tablets at the same time each day throughout the study, and also all subjects will be asked to record daily symptom in a subject diary on a daily basis.

Inclusion Criteria:

1. Subjects aged between 20 and 75 years
2. Subjects who had experienced a minimum three-month history of main symptom(heartburn and regurgitation)
3. Subjects were to have normal esophagus confirmed by endoscopy within 14 days prior to randomization
4. Subjects who is able to understand and follow the instructions and is willing to participate throughout the entire study
5. Subjects who voluntarily signed written informed consent form
6. Subjects who agreed to use medically acceptable contraceptives during the period of study
7. Subjects who had experienced heartburn and regurgitation within 7 days before randomization. Entry into study also required that patients had experienced at least mild upper gastrointestinal symptoms on at least 2 days/week or at least moderate upper gastrointestinal symptoms on at least 1 day/week

Exclusion Criteria:

1. Subjects who cannot undergo EGD
2. Subjects who have esophageal stenosis, ulcer stenosis, gastroesophageal varices, Barrett's esophagus, active gastric ulcer, gastrointestinal bleeding or malignant tumor confirmed by EGD
3. Subjects who have erosive esophagitis, acute upper gastrointestinal bleeding, gastric ulcers or duodenal ulcers, acute erosive gastritis within 2 months before randomization. Subjects with gastric or duodenal erosions are allowed to be included.
4. Subjects who have warning symptoms of malignant gastrointestinal tract such as odynophagia, severe dysphagia, bleeding, weight loss, anemia, or bloody stool
5. Subjects with eosinophilic esophagitis
6. Subjects diagnosed with functional dyspepsia, primary esophageal motility disorder, IBS, IBD, etc. or with suspected IBS in the last 3 months
7. Subjects who have a history of gastric acid suppression surgery or upper gastrointestinal, esophageal surgery
8. Subjects who have bipolar disorder, anxiety disorder, panic disorder, somatoform disorder, personality disorder and psychiatric disorders.
9. Subjects who are taking antipsychotic drugs, antidepressants or antianxiety medications
10. Subjects who should continuously administer NSAIDs during the trial.
11. Pregnant or lactating women
12. Subjects with a history of clinically significant hepatic, renal, cardiovascular, respiratory, endocrine and CNS system disorder
13. Subjects with a history of hypersensitivity to the active ingredient or excipients of the study drug, etc.
14. Subjects who participated in the other clinical trial within 4 weeks prior to randomization