All patients who are undergoing EUS with radial type echoendoscope will be asked for an informed consent. Subjects will be randomized to conventional insertion arm and balloon inflated insertion arm. All patients will be sedated according to SNUH endoscopy center protocol. Conventional insertion will be done in conventional insertion group, and balloon inflation before the start of procedure will be done in balloon inflated insertion arm. After the EUS procedure is finished, subject will be moved to a recovery room. As soon as the subject is recovered from sedation, throat pain will be assessed in NRS scale and be recoreded. Information of insertion failure and balloon damage during insertion will be also collected.