Wafer transfer robot

A substrate transfer device is provided to reduce capacity of a motor by performing a linear motion of a radial direction and a rotational motion through a first driving unit and a second driving unit in a robot hand. An arm frame(10) is supported in an elevating shaft and a robot hand(15) moves to the top and bottom of the elevating shaft. The robot hand comprises a first robot arm, a second robot arm, a first driving unit, a second driving unit and a controller. The first robot arm(12) is pivotally supported in the arm frame. The second robot arm(13) is pivotally supported in the end part of the first robot arm. The first driving unit(20) rotates the robot hand according to the rotation of the first robot arm. The second driving unit(30) expands and contracts the robot hand toward the radial direction according to the rotation of the second robot arm. When the robot hand is rotated, the controller operates the first driving unit and stops the second driving unit. When the robot hand is expanded and contracted toward the radial direction, the controller operates the first driving unit and the second driving unit.