An infrared thermometer capable of measuring a body temperature in no contact with a human body, comprising: a main unit incorporating an infrared sensor; a distance sensor configured to detect a distance between the main unit and the human body when the main unit approaches the human body; and a controller configured to calculate the body temperature of the human body based on quantity of infrared from the infrared sensor when the distance sensor detects that the distance between the main unit and the human body has become a predetermined distance, the distance sensor comprising: a light source for emitting light; a projector lens for projecting the light of the light source toward the human body; a light receiving sensor; and a light receiving lens that allows the light receiving sensor to receive return light of the light, which is obtained as a result of being reflected by the human body, when the main unit is located at the predetermined distance, characterized in that: the infrared thermometer further comprises a circuit board on which the projector lens, the light receiving lens, and the infrared sensor are mounted; each of the projector lens and the light receiving lens are semi-circular arc-shaped lenses; and the infrared sensor is arranged between the projector lens and the light receiving lens, while the projector lens and the light receiving lens are arranged at symmetrical positions with respect to a center axis passing through the infrared sensor, as a center. a main unit incorporating an infrared sensor; a distance sensor configured to detect a distance between the main unit and the human body when the main unit approaches the human body; and a controller configured to calculate the body temperature of the human body based on quantity of infrared from the infrared sensor when the distance sensor detects that the distance between the main unit and the human body has become a predetermined distance, the distance sensor comprising: a light source for emitting light; a projector lens for projecting the light of the light source toward the human body; a light receiving sensor; and a light receiving lens that allows the light receiving sensor to receive return light of the light, which is obtained as a result of being reflected by the human body, when the main unit is located at the predetermined distance, a light source for emitting light; a projector lens for projecting the light of the light source toward the human body; a light receiving sensor; and a light receiving lens that allows the light receiving sensor to receive return light of the light, which is obtained as a result of being reflected by the human body, when the main unit is located at the predetermined distance, characterized in that: the infrared thermometer further comprises a circuit board on which the projector lens, the light receiving lens, and the infrared sensor are mounted; each of the projector lens and the light receiving lens are semi-circular arc-shaped lenses; and the infrared sensor is arranged between the projector lens and the light receiving lens, while the projector lens and the light receiving lens are arranged at symmetrical positions with respect to a center axis passing through the infrared sensor, as a center. the infrared thermometer further comprises a circuit board on which the projector lens, the light receiving lens, and the infrared sensor are mounted; each of the projector lens and the light receiving lens are semi-circular arc-shaped lenses; and the infrared sensor is arranged between the projector lens and the light receiving lens, while the projector lens and the light receiving lens are arranged at symmetrical positions with respect to a center axis passing through the infrared sensor, as a center.