OBJECTIVES: The monetary evaluation for QALY gain is necessary and important information for decision making about medical or public health policies. Even though there is one empirical research about it, it used direct methods to estimate its WTP and thus it has a lot of problems. This paper aims to study the same purpose but by using Conjoint analysis. METHODS: A survey was conducted in the 2005 fiscal year and questionnaires were distributed and collected from 773 households, of which the return rate was 88%. The subjects are 1,297 adults over age 20. In addition to socio-economic characteristics, in this survey respondents were asked a hypothetical question for Conjoint analysis; whether they would agree to the medical care under the hypothetical situation in regards to cost, duration, the number of patients, and health status. We also performed sensitive analysis in regards to explanatory variables in the estimation equation, discount factors, and QOL evaluation for health status. RESULTS: In all equation, the estimated coefficients of total cost are significantly negative and those of QALY gain are significantly positive. CONCLUSIONS: WTP per QALY gain is estimated to be 635 to 675 thousand Japanese yen or 5773 to 6136 US$ assuming 1US$=110 Japanese yen. Income does not affect WTP per QALY significantly.