The invention discloses a cellphone and a card holder mechanism therefor, and the mechanism is suitable for the cellphone. The mechanism comprises a triggering part which can block a card needle hole of the cellphone, and the triggering part can trigger a card holder of the cellphone to pop out. When the card holder of the cellphone needs to pop out, a card needle can be inserted into the card needle hole, and is pushed towards the interior of the cellphone to push the triggering part. The card needle inserted into the card needle hole is pushed to drive the triggering part to move. When the triggering part moves to a set position, the card holder of the cellphone is triggered to pop out. Because the triggering part can exactly block the card needle hole of the cellphone, water cannot enter the cellphone from the card needle hole with the blocking effect of the triggering part when the cellphone meets with water, thereby greatly improving the waterproof performance of the cellphone.