Therapeutic or preventive agent for nausea/vomiting

The present invention provides a therapeutic or prophylactic agent for preventing nausea and vomiting. The agent includes a morphinan derivative represented by general formula (I): or a pharmacologically acceptable acid addition salt thereof as an active ingredient, (where R represents, for example, a cyclopropylmethyl group, R and R represent, for example, a hydroxy or methoxy group, R and R together form, for example, an -O- bond, R represents, for example, a hydrogen atom, Q represents a substituted or unsubstituted group represented by, for example, the following formula: where X represents, for example, NH or NMe). The compounds of the present invention can be widely used as medicines against vomiting caused by emetic drugs. In particular, the compounds of the present invention are useful as therapeutic or prophylactic agents for preventing nausea and vomiting caused by mu -agonists represented by morphine.