||Urease was the first enzyme to be crystallized and one of the virulence-factor enzyme found in various pathogenic bacteria. Due to the fact that many urinary-tract and gastrointestinal diseases, including cancer, are related to urease activity, urease is very important to the human body. Herein, we report urease activity sensing method by using liposomal vesicles polydiacetylene. Urease plays a role in the last step of the nitrogen mineralization process by catalyzing the hydrolyzation of urea to ammonia and carbamate. Carbamate is unstable and spontaneously decomposes to form a second molecule of ammonia along with bicarbonate. Due to ammonia formation, this reaction tends to increase the pH of the environment and induce the color transition of the liposomal vesicles of polydiaectylene from blue to red. Urease activity sensing using this method is rapid, simple, sensitive, and economical.