A construction machine comprising: a main body; a working device that is mounted on the main body; an engine room that is provided in the main body; an engine that is provided in the main body and stored in the engine room; a post-treatment device that is provided in the main body and purifies exhaust gas of the engine; a cooling fan that is provided in the main body and generates cooling air; electric components that are disposed in the post-treatment device; an upper cover member that is provided above the post-treatment device, capable of covering an opening for maintenance of the post-treatment device, and includes a duct for exhausting air in the engine room to an outside; and characterized in that a cover member that is provided at a lower portion of the upper cover member and covers the electric components, the construction machine further comprises: an inflow side opening that is provided in a first end of the cover member located on an upstream side of a flow of cooling air generated by the cooling fan, and allows the cooling air to flow therein; an inflow side guide section that smoothly guides the cooling air flowing in from the inflow side opening to inside of the cover member, and is provided in the cover member; and an outflow side opening that is provided in a second end of the cover member located on a downstream side of the flow of the cooling air, and allows the cooling air flowing in from the inflow side opening to flow out, the cover member is formed in a shape along an arrangement form of the electric components, and has a heat radiation opening for radiating heat in the cover member and heat confined between the post-treatment device and the cover member to an outside of the cover member when the engine is stopped, the inflow side guide section expands toward the upstream side of the flow of the cooling air with respect to a space formed between the cover member and the post-treatment device, and having the electric components therein, and a space between the post-treatment device and the cover member is formed so as to narrow from the inflow side opening toward the outflow side opening, and the construction machine further comprises: a support member that is fixed to a mounting member disposed in the post-treatment device; and a fixing section (34, 35) that fixes the cover member to the support member. a main body; a working device that is mounted on the main body; an engine room that is provided in the main body; an engine that is provided in the main body and stored in the engine room; a post-treatment device that is provided in the main body and purifies exhaust gas of the engine; a cooling fan that is provided in the main body and generates cooling air; electric components that are disposed in the post-treatment device; an upper cover member that is provided above the post-treatment device, capable of covering an opening for maintenance of the post-treatment device, and includes a duct for exhausting air in the engine room to an outside; and characterized in that a cover member that is provided at a lower portion of the upper cover member and covers the electric components, the construction machine further comprises: an inflow side opening that is provided in a first end of the cover member located on an upstream side of a flow of cooling air generated by the cooling fan, and allows the cooling air to flow therein; an inflow side guide section that smoothly guides the cooling air flowing in from the inflow side opening to inside of the cover member, and is provided in the cover member; and an outflow side opening that is provided in a second end of the cover member located on a downstream side of the flow of the cooling air, and allows the cooling air flowing in from the inflow side opening to flow out, an inflow side opening that is provided in a first end of the cover member located on an upstream side of a flow of cooling air generated by the cooling fan, and allows the cooling air to flow therein; an inflow side guide section that smoothly guides the cooling air flowing in from the inflow side opening to inside of the cover member, and is provided in the cover member; and an outflow side opening that is provided in a second end of the cover member located on a downstream side of the flow of the cooling air, and allows the cooling air flowing in from the inflow side opening to flow out, the cover member is formed in a shape along an arrangement form of the electric components, and has a heat radiation opening for radiating heat in the cover member and heat confined between the post-treatment device and the cover member to an outside of the cover member when the engine is stopped, the inflow side guide section expands toward the upstream side of the flow of the cooling air with respect to a space formed between the cover member and the post-treatment device, and having the electric components therein, and a space between the post-treatment device and the cover member is formed so as to narrow from the inflow side opening toward the outflow side opening, and the construction machine further comprises: a support member that is fixed to a mounting member disposed in the post-treatment device; and a fixing section (34, 35) that fixes the cover member to the support member. a support member that is fixed to a mounting member disposed in the post-treatment device; and a fixing section (34, 35) that fixes the cover member to the support member.