A foldable bicycle is disclosed herein which can be unlocked to fold. It comprises a main frame having a first connecting rod and a second connecting rod, a first folding joint between the first connecting rod and the second connecting rod and having a first outer shell, a second outer shell, an engaging unit, an elastic member, a press button and a cam locking member, a front wheel rack connected to a front end of the first connecting rod, a front wheel connected to the front wheel rack, and a rear wheel connected to a rear end of the second connecting rod.