This study is designed to examine the effect of benzydamine hydrochloride to postoperative sore throat in pediatric patients. We will spray benzydmaine hydrochloride or normal saline at oral cavity and the tip of endotracheal tube, than compare the prevalence of postoperative sore throat using smartphone application in pediatric patients.

1. postoperative sore throat incidence (over 2) 1; no, 2;mild, 3;moderate, 4;severe
2. scoring of pain with smartphone application (kids pain scale)
3. incidence of use of rescue pain killer

Inclusion Criteria:

• general anesthesia
• intubation require

Exclusion Criteria:

• recent upper airway infection
• could not express the pain