Work rights, just like the rights to work, to free choice of employment, to just and favorable conditions of work, to equal pay for equal work, to free from employment injuries and occupational diseases, to job security, to retirement income security and to protection against unemployment etc., are always have been highly emphasized by national legislation authorities, even by international covenant or convention. Nowadays, in the practice of European welfare states, the measurements for protection of work rights have become the main part in the field of the social security. This article tries to define the scope of social rights and its concept in terms of comprehensive schemes and programs of social security, and then to define the scope of the work rights and its concept in terms of employment security. Therefore, three categories of employment security, i.e. employment promotion, job security, and income support against unemployment as well as their detail measurements, are delineated.