A backdoor apparatus includes a backdoor panel, a rear spoiler and a wiper mechanism. The wiper mechanism includes a motor assembly, a wiper arm and a wiper blade. A motor installation recess is formed in a top portion of the backdoor panel to receive the motor assembly. The motor assembly includes a cover, which covers a portion of a motor, which is exposed from the rear spoiler. The cover has a flange, which covers a top end part of the glass. The cover, which includes the flange, does not contact the glass.