Activated carbon is one solution to overcome the problem of cigarette smoke which is very dangerous for health where durian shell waste is chosen as the base material. Durian shell waste was chosen because it contains high cellulose, lignin, and starch. Its production also reaches 746,805 thousand tons per year. Durian shell waste that had been activated by chemical activation with K2CO3 versus activated carbon is 1:1, 3:2, and 2:1, and by physical activation with N2 was then modified with MgO with variations in concentrations of 0.5%, 1%, and 2% at 450 o C for 30 minutes. Activated carbon and modified activated carbon were then characterized by the Iod Number test, BET test, SEM test, and EDX test. The best non-modified activated carbon was the carbon which was chemical and physically activated at ratio 3:2 with results of 41.56% in yield, 399.44 mg/g in iodine numbers, and 694.13 m 2 /g in surface area. While the best modified activated carbon was at MgO concentration of 2% with a yield of 97%, an iodine number of 625.70 mg/g, and a surface area of 1,029.90 m 2 /g. The CO gas adsorption application, which is the component with the largest contribution in cigarette smoke, and cigarette smoke itself were tested using modified activated carbon. The results showed that 2% modified activated carbon was the best type of activated carbon to degrade CO in 3.89%/gram per minute with an adsorption ability of 0.215%. This activated carbon was also able to purify the air from the cigarette in 8.04%/gr activated carbon per minute with an adsorption ability of 0.87%.