A first and second guide block pieces retain a plurality of electronic components in an electronic component retention space formed and fixed on a shuttle plate by using a position determination hole formed in advance in accordance with a distance between a pair of opposing corners of a bottom surface of an electronic component, and by emitting light ranging from one end portion to the other end portion of the shuttle plate along an upper surface of a plurality of electronic components interposed and retained between the electronic component interposing-and-retaining portions along longitudinal directions of the first and second guide block pieces, an optical sensor detects that the emitted light is blocked by an irregularly inclined electronic component.