Research on capsule shells has been developed to replace gelatin capsule because it made from pig skin, so it is not halal for consumption. With this problem, carrageenan is used as a substitute for gelatin, because it has properties as a gelling agent but still has a weakness that is not stable in stomach. The purpose of this study was to use microalgae Spirulina platensis because it contains polyhydroxybutyrate (PHB) which are the kind of polymer to improve performance as a drug delivery agent and prolongs the dissolution of the drugs so that the drug will be released into the intestine. The formulation of the solution that used in this research is variation of Spirulina platensis biomass (1%, 1.5%, 2%, 2.5%, 3%) (w/v). The best formulation was determined by capsule shell performance when characterization tests, such as moisture content test, pH, resistance in water, durability in acid solution test, and flexibility. This parameter follow Departemen Kesehatan RI. The best concentration of S. platensis in this research is 3% (w/v), with characterization that obtained as follows: moisture content is 15.77%, pH is 6.5, dissolve in water in 31 minutes 25 seconds, dissolve in acid environment in 35.23, and flexible when merged between cap and body. This capsule can survive in acid condition at pH 1.2 for 75 minutes and release 61.30% of drugs, the at pH 4.5 release 54.90% of drugs at 120 seconds, and the last at pH 6.8 can release 89.58% of drugs. The concentration of biomass affect to the thickness of capsule shell, disintegration time of capsule, and time for dissolution of the capsule shell. With these parameters, it is expected that the capsule form will have stiff and strong structure and not easily degraded at acid environment, so the drug will be released at intestine.