A solder testing apparatus comprising image processing means for performing image processing on an image of an appearance of a soldered portion to identify shape characterizing amounts for the soldered portion; and defect determining means for performing good/bad determination on the soldered portion from data derived by the image processing means and data from test parameter storing means for storing shape characterizing amounts at design time, wherein tested-object standard shape estimating means is included for extracting shape characterizing amounts of a non-defective soldered portion by statistically processing shape characterizing amounts for soldered portions identified by the image processing means, and defect determining parameters stored in the test parameter storing means are updated based on standard shape values from the tested-object standard shape estimating means, so that a highly reliable test is realized by setting defect determining parameters based on actual shapes and dimensions of leads and pads of electronic components on a printed circuit board.