A screen printer comprising: a conveyance device configured to convey a board; a board holding device configured to position a conveyed board at a printing position; a stencil holding device configured to attach a stencil above the held board; a squeegee device configured to fill pattern holes of the stencil with solder paste; a board raising and lowering device configured to raise and lower the board positioned by the board holding device; and a control device configured to perform drive control of each the above devices, the control device including a standby printing processing section configured to raise the board from below with respect to the stencil such that the board contacts the stencil, stand by in a state with solder paste filled in the pattern holes, and lower the board to separate the board from the stencil in accordance with a board conveyance signal.