A handheld electronic device includes first, second and third bodies, first and second pivot members pivot to the first body and a gear set. The second body having a pillar is slidably disposed on the first pivot member. The third body having a rack is slidably disposed on the second pivot member, the second body stacked between the first and third bodies. The gear set is disposed on the first body and coupled with the pillar and the rack. When the third body moves relatively to the first body along a first operation direction for driving the second body to move relatively to the first body along a second operation direction opposite to the first operation direction to be exposed by the third body, the first and second pivot members rotate relatively to the first body to drive the second and third bodies to tilt relatively to the first body.