A handheld electronic device including a first body, a second body, a sliding module, and a shielding member is provided. The sliding module drives the first body and the second body transforming between a retracting state and a spreading state. The sliding module includes a sliding member, a fixing member and a driving member. The sliding member has an opening and when the first body and the second body configure in the spreading state, a part of the opening is exposed. The shielding member is coupled to the driving member. When the first body and the second body are transformed from the retracting state to the spreading state, the driving member drives the shielding member sliding with respect to the sliding member to shield the part of the opening.