The purposes of this study are to develop a chitosan suspension for the carbon dioxide (CO2) concentration indication of packaged food and to investigate the changes in the CO2 indication corresponding to 2-amino-2-methylpropan- 1-ol (AMP) or 2-aminoethanol (monoethanolamine, MEA) addition. Chitosan suspension was prepared by adding chitosan (0.1, 0.2, and 0.4%) to distilled water and subsequently the pH of the suspension was adjusted to 7.0 after the addition of AMP or MEA. Changes in the pH and the turbidity of the chitosan suspension were measured over time under exposure in a normal atmosphere or 100% carbon dioxide environment. The pH of the chitosan suspension exposed at 100% carbon dioxide environment decreased rapidly up to approximately 6.3 in the initial CO2 exposure. The transmittance values of 0.1 and 0.2% chitosan suspensions with 5% AMP increased from 32 to 99% and from 19 to 86%, respectively. The addition of 5% AMP improved the visual indication performance of the chitosan suspension since it increased significantly the width of the transmittance value before and after CO2 exposure. The chitosan suspension with AMP has a potential to be used as a quality indicator of the packaged foods which produce carbon dioxide during storage and distribution.