To provide an embroidery data processor capable of preparing preliminary sewing data optimum for a block based on the preliminary sewing attribute data even when setting position data of a needle point within the block after the block is expanded/contracted by storing the preliminary sewing data in a corresponding manner to the block as the preliminary sewing attribute data.
If running data is present before the data of Block A, Block B and Block C (S1: YES), whether or not the running data present before Blocks A to C is included in an area of either of Blocks A to C is determined (S2), and if the running data is included in the area of either of Blocks A to C (S2: YES), it is stored in a RAM 25 in the corresponding manner to the block as the preliminary sewing attribute data of the block including the data.