To provide a bump height measuring method capable of measuring the height of a projection bump formed on a work surface fast with high precision.

This method includes a lighting process wherein an area including the bump on the substrate W is irradiated with light at a specific elevation angle from two relative directions and the shadow of the bump is projected on the substrate W, an image pickup process wherein an image of the area R on the substrate W lit through the said process is picked up and an image signal having the shadow of the bump is outputted, a shadow extracting process wherein a binarized image signal generated by extracting only the shadow of the bump from the image signal is outputted, and a shadow length arithmetic process wherein the length between the tips of the shadows of the bump in the two directions is found from the threshed processed shadow image signal and the height of the bump is found from the length of the shadow and the elevation angle.