The invention provides a semiconductor processing apparatus having a high throughput capable of appropriately coping with the positional displacement that may occur during transfer of the wafer after correcting the position thereof, without slowing down the transfer speed of the wafer. A position correction quantity of the wafer with respect to a vacuum robot is computed based on the outputs of a .theta. axis sensor for detecting the interception angle of the wafer during rotation of the vacuum robot and an R axis sensor for detecting the interception distance of the wafer during expansion and contraction of the vacuum robot. If the position correction quantity exceeds a predetermined standard value, an operation to change the position data is performed, and if the distance data obtained based on the outputs from the .theta. axis sensor and the R axis sensor exceeds a predetermined permissible value, it is determined that a displacement error has occurred and the operation is stopped.