The claim of a patent defines the scope of patent right and provides crucial information on patent value. However, most empirical research uses only the number of claims as an indicator of patent value. We show that the breadth of a claim of Japanese patents, measured by the inverse of claim length, has significant explanatory power for patent value measured by applicant forward citations. Indeed, the explanatory power of claim breadth is comparable with that of the number of claims. The predictive power of claim breadth is stable for all quantiles in the discrete technology area, while it is far more significant for top-ranked patents in the complex technology area.