The observed gender pay gap seemingly constitutes evidence of inequality in the labour market. The persistence of this gap has generated considerable debate over the extent to which it reflects discrimination and the extent which it can be explained by productivity-related characteristics. However, measurement of wage `discrimination' seems inadequate because it implicitly requires an assumption that the wage gap arising from differences in individual characteristics are distinct from those arising from differential remuneration of those characteristics. Therefore the purpose of this dissertation is to explore male-female wage differentials, with particular concern to measuring wage `discrimination'. This dissertation sets out to compare the earnings differentials between full-time working women and men in Britain and Japan and the reasons for those differences. These two countries make an interesting contrast. In both countries, women have continued to earn considerably less than men, but the wage gap among full-time workers is much bigger in Japan than in the Britain. In Japan seniority and personal appraisals are much more important than job content in determining wages, whereas in Britain earnings are more closely related to the content of the job. Because in Japan there are limited microdata available, the focus was made on using UK data - Labour Force Survey (LFS) and National Child Development Studies (NCDS) to highlight inequalities and identify where these inequalities are located. I had to rely on the published study of Nakata (1997) and made comparisons with Britain by constructing a model which is as similar as possible to that used by Nakata (1997), based on data from the British LFS. The main findings are that: (1) More than half of the Japanese female-male wage gap (48% of male wages) is explained by differences in individual characteristics (27%) rather than differences in labour market return (21%). By contrast, almost all the gender pay gap in Britain is due to differential rewards between men and women. (2) Wage `discrimination' is responsible for about 12% to 23% of male wages in Britain and 21% in Japan. In both countries, the unexplained gap is mainly due to gender differences in reward for age (or total work experience in the UK context). (3) Occupation-related factors including occupational segregation are also the main factors in unequal pay in Britain. The thesis draws out the value of analysis based on nationally representative microdata and makes some progress in measuring wage `discrimination' for analyses of British gender wage differentials. However, detailed analysis for Japan was not carried out because of the paucity of microdata in Japan. This dissertation emphasizes the importance of the release of microdata and the need for detailed information in surveys, to enable scholars to conduct detailed investigations of gender inequalities in Japan.