Rocuronium preparation causing less pain, method for producing the same, and method for reducting and/or alleviating vascular pain to be induced using the same

Provided is a rocuronium preparation that makes it possible to suppress vascular pain. This rocuronium preparation is characterized by containing rocuronium and a buffer and having titratable acidity of 100 mEq or less. The buffer may be an acetate buffer, citrate buffer, formate buffer, tartrate buffer, phosphate buffer, glycine-hydrochloric acid buffer, citrate-phosphate buffer, or the like.