A gas sensor package, comprising: a first substrate including a metal pattern; a gas sensing element mounted on the first substrate and having a gas sensing part disposed to face a surface of the first substrate; and a protective cap disposed on the first substrate and having a receiving space for protecting the gas sensing element, wherein the protective cap comprises a side wall whose one end is in contact with the first substrate, an upper surface portion on the side wall, and a first ventilation hole; characterised in that said first ventilation hole extends through the side wall and connects the receiving space and an exterior, and wherein the first ventilation hole is in contact with the first substrate wherein the gas sensing element comprises: an element body including a lower surface and a side wall and having a cavity part in the inside thereof; and the gas sensing part is disposed on an external surface of said element body opposite to said lower surface facing said cavity part and including a gas sensing material; and further characterised by comprising a cover member configured to cover an upper surface of the cavity part, wherein the cover member is disposed to cover an upper surface of the side wall of the element body and the upper surface of the cavity part of the element body, wherein a lower surface of the cover member is formed below an imaginary horizontal surface formed by the upper surface of the side wall of the element body, and has a curvature, wherein an upper surface of the cover member has a flat structure. a first substrate including a metal pattern; a gas sensing element mounted on the first substrate and having a gas sensing part disposed to face a surface of the first substrate; and a protective cap disposed on the first substrate and having a receiving space for protecting the gas sensing element, wherein the protective cap comprises a side wall whose one end is in contact with the first substrate, an upper surface portion on the side wall, and a first ventilation hole; characterised in that said first ventilation hole extends through the side wall and connects the receiving space and an exterior, and wherein the first ventilation hole is in contact with the first substrate wherein the gas sensing element comprises: an element body including a lower surface and a side wall and having a cavity part in the inside thereof; and the gas sensing part is disposed on an external surface of said element body opposite to said lower surface facing said cavity part and including a gas sensing material; and further characterised by comprising a cover member configured to cover an upper surface of the cavity part, wherein the cover member is disposed to cover an upper surface of the side wall of the element body and the upper surface of the cavity part of the element body, wherein a lower surface of the cover member is formed below an imaginary horizontal surface formed by the upper surface of the side wall of the element body, and has a curvature, wherein an upper surface of the cover member has a flat structure. an element body including a lower surface and a side wall and having a cavity part in the inside thereof; and the gas sensing part is disposed on an external surface of said element body opposite to said lower surface facing said cavity part and including a gas sensing material; and further characterised by comprising a cover member configured to cover an upper surface of the cavity part, wherein the cover member is disposed to cover an upper surface of the side wall of the element body and the upper surface of the cavity part of the element body, wherein a lower surface of the cover member is formed below an imaginary horizontal surface formed by the upper surface of the side wall of the element body, and has a curvature, wherein an upper surface of the cover member has a flat structure.