Mast cell degranulation inhibitors having a carboxyl group have not been used as medicines for external application, because of their low transdermal permeatibility. If the inhibitors are administered through transdermal application, any adverse side effect on organs in the body which may be produced when administered via an oral route administration could be avoided. Further, some of the mast cell degranulation inhibitors have an extremely poor photostability. This contributes to the difficulty in the development of a medicine for external application comprising the inhibitor. The transdermal permeability and photostability of a mast cell degranulation inhibitor can be improved by using the inhibitor in the form of a salt with an organic amine. Thus, disclosed is a preparation for external application comprising a mast cell degranulation inhibitor. The mast cell degranulation inhibitor and a preparation comprising the mast cell degranulation inhibitor can be improved in photostability.