Screen printer, component mounting line, and screen printing method

A screen printer comprising:

• a mask that has pattern holes formed thereon;
• a substrate holding unit that clamps and holds a substrate at sides by a pair of clamping members below the mask;
• a substrate holding unit moving mechanism that moves the substrate holding unit holding the substrate to contact the substrate with a lower surface of the mask;
• a paste filling unit that fills, with a paste, the pattern holes of the mask contacted with the substrate by the substrate holding unit moving mechanism;
• mask suction portions that are provided in the pair of clamping members and that suck the mask being contacted with the substrate;
• and
• a control unit that controls the mask suction portions to keep sucking the mask when the substrate holding unit moving mechanism moves the substrate in a direction away from the mask to perform plate releasing after the pattern holes of the mask are filled with the paste, and to release the suction of the mask in a state in which the mask sucked to the mask suction portions maintains a posture parallel to the substrate after the movement of the substrate is started.