Calcium alginate gel (CAG) is easy to form and is nontoxic. Therefore, it is expected to use for a Drug Delivery System (DDS). In DDS, the particle diameter is required to be μm or nm. To formation CAG micro particle, microfluidic method has attracted attention. In this work, Isoamyl alcohol was used to improve the production stability of CAG in microfluidic method. Isoamyl alcohol can dissolve calcium chloride and cannot dissolve sodium alginate. Thus, the sodium alginate solution and the calcium chloride solution surely react. In this report, the droplet were formed at different types and different concentrations of sodium alginate and their particle size were investigated. As results, droplet size and formation process of alginate droplet changed depending on sodium alginate type and concentration. Under the condition measured this report, the diameter of the alginate droplet were found to be in the range between 200 and 300 μm.