<p>To provide an electric connection box of a novel structure capable of providing a structure of positioning one case and the other case with respect to each other and a structure of preventing erroneous assembling while achieving a size reduction and space saving, positioning bosses (84 and 88) and positioning recesses (45 and 48) are provided in first corner portions (44 and 82) and second corner portions (46 and 86) opposing in a direction of a diagonal line of a hollow case (102). An inside dimension of the positioning recess (48) provided in the second corner portion (46) is set larger than an inside dimension in the direction of the diagonal line of the positioning recess (45) provided in the first corner portion (44). A rib protrusion (94a) of the positioning boss (84) in the second corner portion (46) is allowed to be fit into a fitting recess groove (60) provided to the positioning recess (48) in the second corner portion (46) and also allowed to interfere with inner protrusions (52 and 52) provided to the positioning recess (45) provided in the first corner portion (44).
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