A void evaluation apparatus in a solder includes an evaluation function calculation unit for calculating a solder evaluation function by using a pixel value pi contained in the voids that is set to 1 and the pixel value pi not contained in the voids is 0 for each pixel constituting an image in the solder, and by using a weight function w(ri), which is maximum at a solder center (ri=0), and is 0 at a maximum radius (ri=r0) for a distance ri from the solder center. The apparatus further has a void evaluation unit for evaluating that the influence of voids is larger as the evaluation function is relatively larger for the each solder. ∑ i = 1 N ⁢ ⁢ w ⁡ ( r i ) ⁢ p i ∑ i = 1 N ⁢ ⁢ w ⁡ ( r i ) × 100 i: pixel number (1−N) pi: pixel value (0 or 1) w(ri): weighting function