A digitizing method which controls the movement of at least one axis (X- or Y-axis) by the numerical control based upon the passage data, which controls the movement of another axis (Z-axis) by the profile control, and which monitors the current positions of the axes in order to obtain three-dimensional data on an object. A numerical controller (101) performs numerical control based on NC data supplied from an NC tape (106) to move a tracer head (105) in the X-and Y-directions. A profile controller (102) performs the control relying upon displacement components (εx, εY, εz) of the axes generated by the tracer head, to produce a speed instruction V z of the Z-axis, and to move the tracer head in the direction of Z-axis. The numerical controller (101) counts the number of pulses (F z ) generated every after a motor (M z ) that drives the profile control axis (Z-axis) has made rotation of a predetermined angle, and obtains the current position of the profile control axis. The numerical controller further obtains an instruction position of the numerical control axes (X-, Y-axes) using the passage data, and subtracts servo delay amounts (E x , Ey) which are the contents of error registers (ER . , ERy) from the instruction position, in order to obtain a current position expressed by a mechanical position. Thereafter, the current positions of the axes represented by mechanical positions are stored in a memory (101b) every after a predetermined period of time.