In this study, we investigated mass of non-structural carbohydrate (TNC) in root system, in terms of inter-specific variation with different sprouting properties and seasonal changes. The study site is a secondary broadleaved-forest (ca. 25 years old), close to Ogawa Forest Reseave, Ibaraki prefecture. Materials were single-stem trees of Quercus serrata and Prunus verecunda. We sampled totally 24 woody tissues from coarse root of these trees covering whole range of their size variation(dbh=2.6~21.2cm), in July, September and December of 2011. We extracted ethanol-soluble sugar and starch, and quantified density of TNC. The result showed that both species had highest content of sugar in July with decreasing trend thereafter. No distinct shift from sugar to starch was found. TNC in root of P. verecunda increased with above ground biomass (AGB) but peak out over a certain value of AGB. In contrast, that of Q. serrata showed exponentially increasing trend with AGB. These results well explain the life history of these species in relation to growth and sprouting: P. verecunda grows faster, while Q. serrata grows slower but has greater capacity of sprouting.