The study reported here was designed to investigate how foreigners understand euphemistic expressions in Japanese which is a second language for them. In experiment, twenty students from foreign countries were adopted in order to make it clear what kinds of factors affect on the degree of understanding of euphemistic expressions. Four types of euphemistic expressions which mean an invitation, a request, a refusal, or a sarcasm were used in the form of dialogs. The results showed that the euphemistic expression of invitation was easy for them to understand, but the sarcastic expression was difficult. Furthermore, it was also suggested that two factors were critical for the degree of understanding of Japanese euphemistic expressions: (a) how long they have been learning Japanese with no relation to the place of learning, and (b) whether they had experiences in receiving such euphemistic expressions from the Japanese.