The agricultural and food processing sectors have been one of major production activities in Thailand because their employment are among the largest portions in labor market. Also both sectors have a high magnitude of Leontief multipliers, showing their substantial degrees of spillovers to other industries. To examine the network of both sectors' contributions to Thai economy, this study constructed the Social Accounting Matrix (SAM) by extending the official Input-Output table of 2010. The computational technique of Structural Path Analysis (SPA) was then applied to the constructed SAM. The results generated by SPA unveiled details of supply chains connecting agricultural activity, food processing sector, employment of factors of productions and household's incomes. Specifically, based on the most detailed classifications of the official Input-Output table, the SPA results revealed and quantified the broad and in-depth details of supply chains of tapioca milling, rice milling, canning preserving of meat, drying and noodles and similar products. These outcomes would be useful for policy analysis, particularly on both the quantification of propagation mechanism influenced by production's expansion and the magnitude of contraction along the supply chain caused by unexpected negative shocks.