C4 chemicals are very important for every-life. Among them, succinic acid derivative products such as 1,4-butanediol, gamma-butyrolactone, and N-methylpyrrolidone. Currently, it is synthesized from the crude-oil. But the amount of crude oil is limited, and it causes the environmental problem. In order to overcome this problem, sustainable and eco-friendly process is required. One of them is biological process using bacteria. Bacteria could produce chemicals generally such as lactic acid, succinic acid and etc with mild condition, suitable media and carbon source. Metabolic engineering is the optimizing and regulatory processes within cell to increase the cells’ production of a certain substance. Using metabolic engineering, desired products could be produced easily. In order to produce various C4 chemicals, metabolic engineering was performed. Chapter 1 is an overview of the C4 world market size, utilization and explanation the chemical method for the synthesis of C4 chemicals. Chapter 2 reports the increasing succinic acid production in Mannheimia succiniciproducens. Chapter 3 reports the metabolic engineering for the production of malic and fumaric acids in Mannheimia succiniciproducens. Chapter 4 reports the production of 4-hydroxybutyric acid by introduction of 4-hydroxybutyric acid synthesis pathway production using high succinic acid producer and chemical conversion of 4-hydroxybutyric acid to gamma-butyrolactone which is a useful C4 chemical. Chapter 5 reports the production of 4-hydroxybutyric acid under micro-aerobic condition using Escherichia coli. Chapter 6 reports systems metabolic engineering for production of 4-hydroxybutyric acid in micro-aerobic conditition.