Endoscopic submucosal dissection (ESD) permits the resection of large gastrointestinal epithelial neoplasms and neoplasms with submucosal fibrosis in an en bloc manner. However, the high frequency of complications accompanying ESD and its complex processes suggests that the process requires improvement. A total of 22 consecutive patients with gastrointestinal epithelial neoplasms were enrolled during a 6-month period to evaluate a novel endosurgical knife for ESD. This novel knife is known as the “splash-needle,” and it is thin, short needle with a water-irrigation function. The technical results revealed that the rates of bloc resection and en bloc resection with tumor-free lateral/basal margins (R0 resection) were 91% (20/22) and 82% (18/22), respectively. There was no significant bleeding or perforation during or after ESD. The median operation time was 60 minutes (range, 20 to 210). The splash-needle is a promising novel endosurgical knife that is useful for less complicated ESD. The accumulation of knowledge and cases verifying its usefulness is necessary, and a study comparing the knife with first-generation endosurgical knives is also warranted.