An inhaler comprising: a housing having one surface, the other surface opposite to the one surface, and a plurality of side surfaces connecting the one surface and the other surface; a canister which is mounted interchangeably inside the housing and accommodates an inhalable composition; a reservoir which is positioned inside the housing and to which one side of the canister is connected; and a lever having one side forming a portion of the housing , and the other side being movable between a bottom surface of the canister and the other surface of the housing , wherein, when one side of the lever is pressed, the other side of the lever moves the canister in a direction toward the reservoir and some of the inhalable composition in the canister are stored in the reservoir , wherein the lever further comprises: a first lever member which forms a portion of one side surface of the plurality of side surfaces of the housing ; and a second lever member which extends from the first lever member toward the canister , and wherein, when the first lever member is pressed, the second lever member moves in a first direction from one side of the housing toward the canister to be inserted between the bottom surface of the canister and the other surface of the housing , and the canister moves in a second direction from the other surface to the one surface of the housing . a housing having one surface, the other surface opposite to the one surface, and a plurality of side surfaces connecting the one surface and the other surface; a canister which is mounted interchangeably inside the housing and accommodates an inhalable composition; a reservoir which is positioned inside the housing and to which one side of the canister is connected; and a lever having one side forming a portion of the housing , and the other side being movable between a bottom surface of the canister and the other surface of the housing , wherein, when one side of the lever is pressed, the other side of the lever moves the canister in a direction toward the reservoir and some of the inhalable composition in the canister are stored in the reservoir , wherein the lever further comprises: a first lever member which forms a portion of one side surface of the plurality of side surfaces of the housing ; and a second lever member which extends from the first lever member toward the canister , and wherein, when the first lever member is pressed, the second lever member moves in a first direction from one side of the housing toward the canister to be inserted between the bottom surface of the canister and the other surface of the housing , and the canister moves in a second direction from the other surface to the one surface of the housing . a first lever member which forms a portion of one side surface of the plurality of side surfaces of the housing ; and a second lever member which extends from the first lever member toward the canister , and wherein, when the first lever member is pressed, the second lever member moves in a first direction from one side of the housing toward the canister to be inserted between the bottom surface of the canister and the other surface of the housing , and the canister moves in a second direction from the other surface to the one surface of the housing . <EOS>