This study is designed to determine the efficacy and safety of DWP14012 compared to a placebo following a once-daily oral dose of DWP14012 at 20 mg, 40 mg, or placebo for 4 weeks in patients with NERD.

Inclusion Criteria:

1. Male and female adults aged 19 to 75 years, both inclusive, at the date of obtaining informed consent
2. Subjects with no mucosal break(s) according to Los-Angeles grade on EGD performed at the same site within 2 weeks prior to Visit 1
3. Subjects who have experienced heartburn for at least 12 weeks prior to Visit 1
4. Subjects who have completed all symptom assessments (heartburn, acid regurgitation) in the subject diary from 7 days to 1 day prior to Visit 2
5. Subjects who have experienced one of the following symptoms according to the symptom assessments in the subject diary from 7 days to 1 day prior to Visit 2
6. Subjects who have reported at least moderate burning sensation in the esophagus (behind the breastbone) for heartburn symptoms for at least 4 days
7. Subjects who have reported at least moderate pain in the esophagus (behind the breastbone) for heartburn symptoms for at least 4 days
8. Subjects who are capable of understanding the provided information and able to comply with all the study procedures including filling out the subject diary and questionnaire throughout the study
9. Subjects who voluntarily decide to participate in the study and sign the informed consent form

Exclusion Criteria:

1. Subjects who have Barrett's esophagus, gastroesophageal varix, viral/fungal gastrointestinal infection, esophagostenosis, ulcer stenosis, active peptic ulcer, gastrointestinal bleeding, or a malignant tumor identified on EGD performed within 2 weeks prior to Visit 1

2. Subjects who have warning symptoms of malignant gastrointestinal tract diseases such as odynophagia, severe dysphagia, bleeding, weight loss, anemia, or hematochezia at Visit 1 (However subjects who have additional warning symptoms besides typical symptoms of gastroesophageal reflux disease [GERD] may be included if the result of endoscopy, etc. is negative for the presence of tumor.)

3. Subjects with Zollinger-Ellison syndrome at Visit 1

4. Subjects with eosinophilic esophagitis at Visit 1

5. Subjects who are diagnosed with erosive GERD, acute upper gastrointestinal bleeding, gastric ulcer, or duodenal ulcer within 8 weeks prior to Visit 1

6. Subjects who are diagnosed with FD, FH, RH, primary esophageal motility disorder, IBS, and IBD within 12 weeks prior to Visit 1

7. Subjects who had a surgery to reduce gastric acid secretion, or gastric or esophageal surgery (e.g., gastrectomy, mucosal resection, etc.) (Except, simple perforation surgery and endoscopic resection of benign tumors)

8. Subjects who have a clinically significant disease of hepatic, renal, neurologic, respiratory, endocrine, hemato-oncologic, cardiovascular or urinary system at Visit 1

9. Subjects who have history of alcohol or other drug abuse within 1 year prior to Visit 1

10. Subjects diagnosed with malignant tumor within 5 years prior to Visit 1 (Subjects completely healed for ≥5 years from the last treatment without recurrence are allowed to be enrolled.)

    • Subjects with cured basal cell carcinoma of the skin or carcinoma in situ of the cervix are allowed to be enrolled regardless of time period
    • Subjects with a history of digestive malignant tumor are excluded regardless of the time period

11. Subjects who have or had bipolar disorder, anxiety disorder, panic disorder, somatoform disorder, personality disorder, or other clinically significant psychiatric disorders

12. Subjects with scleroderma (systemic sclerosis) or systemic lupus erythematosus

13. Subjects who have hypersensitivity, or medical history of clinically significant hypersensitivity, to any components of the IP

14. Subjects with hereditary disorders including galactose intolerance, Lapp lactase deficiency, glucose-galactose malabsorption, etc.