To provide a suction device and a workpiece conveying device capable of shortening the time required for evacuating a suction pad to a predetermined degree of vacuum.

The workpiece conveying device 1 includes the suction device 2 for gripping a workpiece w by vacuum drawing the suction pad 21 arranged in a surface of the workpiece w, the object to be conveyed, by a vacuum pump 22 and a structure member 3 having a cross bar 31 for supporting the suction pad 21, a driving arm 32 for moving the cross bar 31 and a supporting member 33 for movably supporting a driving arm 32. The suction device 2 includes a vacuum tank 4 formed in the supporting member 33, a first air intake flow passage 5 arranged between the vacuum tank 4 and the suction pad 21, a solenoid valve 6 arranged in the first air intake flow passage 5 and a second air intake flow passage 7 arranged between the vacuum tank 4 and the vacuum pump 22.