A deck board pushing and clamping device is provided for pushing an unsecured board along its length into contact with a secured board which has been secured to a support joist, while simultaneously clamping the device to the support joist, thereby to clamp the unsecured board between the clamped device and the secured board, for one person ease in properly and efficiently securing the clamped board to the support joist with nails. The device uses a handle lever to operate a cam member onto which is attached a scissor-like pushing mechanism as well as a clamping mechanism. As the cam member is rotated with the handle lever, the scissor-like pushing mechanism moves a strike plate into contact with the unsecured board while the clamping mechanism is simultaneously raised into a clamping position around the support joist. A locking pin secures the device in a temporarily clamped position, thereby permitting one person to minimize a gap between the unsecured board and the secured board, and subsequently to use both hands to secure the unsecured board to the support joist with nails.