A processing target conveying device comprising: a stocker which is configured to accommodate a plurality of processing targets; a conveying unit that is configured to take out one of the processing targets, which are accommodated in the stocker, from the stocker; a moving mechanism that is configured to move the conveying unit in a three-dimensional direction relative to the stocker; and a controller that is configured to control the moving mechanism, wherein an adapter having a first engagement projection formed at one end in a first direction and a second engagement projection formed at the other end on a side opposite to the one end is configured to be attached to the processing target, and the conveying unit includes: a conveying unit body; a first hook which extends in a second direction orthogonal to the first direction from the conveying unit body and in which a first engagement recess configured to engage with the first engagement projection is formed at a distal end thereof; a second hook which, at a position facing the first hook in the first direction, extends in the second direction from the conveying unit body and in which a second engagement recess configured to engage with the second engagement projection is formed at a distal end thereof; a first spring that is configured to apply elastic force to the first hook so that the distal end of the first hook moves toward the second hook when the first engagement projection is positioned in the first engagement recess; and a second spring that is configured to apply elastic force to the second hook so that the distal end of the second hook moves toward the first hook when the second engagement projection is positioned in the second engagement recess. a stocker which is configured to accommodate a plurality of processing targets; a conveying unit that is configured to take out one of the processing targets, which are accommodated in the stocker, from the stocker; a moving mechanism that is configured to move the conveying unit in a three-dimensional direction relative to the stocker; and a controller that is configured to control the moving mechanism, wherein an adapter having a first engagement projection formed at one end in a first direction and a second engagement projection formed at the other end on a side opposite to the one end is configured to be attached to the processing target, and the conveying unit includes: a conveying unit body; a first hook which extends in a second direction orthogonal to the first direction from the conveying unit body and in which a first engagement recess configured to engage with the first engagement projection is formed at a distal end thereof; a second hook which, at a position facing the first hook in the first direction, extends in the second direction from the conveying unit body and in which a second engagement recess configured to engage with the second engagement projection is formed at a distal end thereof; a first spring that is configured to apply elastic force to the first hook so that the distal end of the first hook moves toward the second hook when the first engagement projection is positioned in the first engagement recess; and a second spring that is configured to apply elastic force to the second hook so that the distal end of the second hook moves toward the first hook when the second engagement projection is positioned in the second engagement recess. a conveying unit body; a first hook which extends in a second direction orthogonal to the first direction from the conveying unit body and in which a first engagement recess configured to engage with the first engagement projection is formed at a distal end thereof; a second hook which, at a position facing the first hook in the first direction, extends in the second direction from the conveying unit body and in which a second engagement recess configured to engage with the second engagement projection is formed at a distal end thereof; a first spring that is configured to apply elastic force to the first hook so that the distal end of the first hook moves toward the second hook when the first engagement projection is positioned in the first engagement recess; and a second spring that is configured to apply elastic force to the second hook so that the distal end of the second hook moves toward the first hook when the second engagement projection is positioned in the second engagement recess.