To provide a motor driver for driving a motor surely and generating an index signal effectively.

An output of a Hall element 40 is fed to an index detection circuit 42. The index detection circuit 42 detects the timing of 60° of the Hall element 40 from a waveform of another phase output of a motor coil and holds as a sample sum obtained by adding a given value to the output value of the Hall element 40. Then the sample hold value and the output of the Hall element 40 are compared to obtain an index signal. The output of the Hall element 40 is fed as an input to a driving control circuit 22 to generate a driving pattern at, thestart.