To investigate the mechanism of mechanical hydrocarbon extraction from microalgae, B. braunii was disrupted by a bead mill and a Jet-Paster. The particle size distribution and morphology of the treated microalgae and the amount of the hydrocarbon extracted with n-hexane were measured, and the polymers around its colonies were observed. As a result, the particle size and morphology of the samples changed and the hydrocarbon extraction rates increased with disruption. Although the morphologies between samples disrupted by the Jet-Paster and bead mill were similar tendency, the extraction rate of the sample treated at 4800 rpm by the Jet-Paster showed higher than that of the sample treated by bead mill. This is because that almost all the polymers around colonies were broken by the Jet-Paster.