A coating die used to apply a first coating material and a second coating material onto a material to be coated, the coating die comprising: a first body; a second body; a first manifold that temporarily stores the first coating material; a second manifold that temporarily stores the second coating material; a discharge port that is disposed between the first body and the second body, that is longer in a second direction that intersects a first direction in which the coating die and the material to be coated are arranged, and through which the first coating material and the second coating material are discharged toward the material to be coated; an intermediate member that is provided between the first body and the second body and that becomes thinner toward the discharge port such that the first body and the second body come closer to each other; a first shim provided between the first body and the intermediate member to define a first flow passage provided from the first manifold toward the discharge port; a second shim provided between the second body and the intermediate member to define a second flow passage provided from the second manifold toward the discharge port; and a confluence passage in which the first flow passage and the second flow passage join together and that communicates with the discharge port, characterised in that, the first shim comprises a pair of first arms arranged in the second direction between which the discharge port is located, the second shim comprises a pair of second arms arranged in the second direction between which the discharge port is located, each first arm comprises, at the tip, a first female portion formed by cutting out at least part of the first arm in a thickness direction of the first shim, and a first male portion that is arranged with the first female portion in the second direction and thicker than the first female portion, each second arm comprises, at the tip, a second female portion formed by cutting out at least part of the second arm in a thickness direction of the second shim, and a second male portion that is arranged with the second female portion in the second direction and thicker than the second female portion, and the first female portion and the second male portion are engaged with each other, and the first male portion and the second female portion are engaged with each other. a first body; a second body; a first manifold that temporarily stores the first coating material; a second manifold that temporarily stores the second coating material; a discharge port that is disposed between the first body and the second body, that is longer in a second direction that intersects a first direction in which the coating die and the material to be coated are arranged, and through which the first coating material and the second coating material are discharged toward the material to be coated; an intermediate member that is provided between the first body and the second body and that becomes thinner toward the discharge port such that the first body and the second body come closer to each other; a first shim provided between the first body and the intermediate member to define a first flow passage provided from the first manifold toward the discharge port; a second shim provided between the second body and the intermediate member to define a second flow passage provided from the second manifold toward the discharge port; and a confluence passage in which the first flow passage and the second flow passage join together and that communicates with the discharge port, characterised in that, the first shim comprises a pair of first arms arranged in the second direction between which the discharge port is located, the second shim comprises a pair of second arms arranged in the second direction between which the discharge port is located, each first arm comprises, at the tip, a first female portion formed by cutting out at least part of the first arm in a thickness direction of the first shim, and a first male portion that is arranged with the first female portion in the second direction and thicker than the first female portion, each second arm comprises, at the tip, a second female portion formed by cutting out at least part of the second arm in a thickness direction of the second shim, and a second male portion that is arranged with the second female portion in the second direction and thicker than the second female portion, and the first female portion and the second male portion are engaged with each other, and the first male portion and the second female portion are engaged with each other.