A study on the effect of the biodegradability of the composting bulking agent in the swine manurecomposting was carried out in a batch system. The purpose of this study is to prove the effect of the biodegradability of the composting-bulking agent on the efficiency of the composting. In this study, it is the lignins: Klason-Lignin in the volatile solid that the index of the biodegradability of the composting-material mixes which are pig manure-rice straw pig manure-sawdusts pig manuremixture of rice and ricestraw (2:1) pig manure-mixture of rice and sawdust (1:1). It was carried out in the same condition (moisture contents, air supply rate, C/N ratio, initial input weight, porosity-structure) except the biodegradability of the raw material mixes. One of the results from this study is that the biodegradability of the bulking agent in the sense of the VS lignin content is not an insignificant factor in composting reaction. The less contents of the lignin in VS, the more efficiencies of the cornposting reaction in use of these parameters for the degree of the reaction: temperature, the trends of the ash contents, the change pattern of the C/N ratio. Under some assumptions, it is able to induce rough model on the relation of the VS lignin contents with the efficiency of the degradability. In this model, the biodegradability of the bulking agent is not an insignificant factor however, it is flexible within some degrees of range.