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.