A construction machine comprising: a lower traveling body; and an upper slewing body slewably mounted on the lower traveling body, the upper slewing body including: an upper frame as a base; an engine compartment provided on a rear end region of the upper frame to house an engine and an engine-related device (14, 15, 16); a cabin provided on a front region of the upper frame in one of right and left regions of the upper frame; a central foothold for maintenance work, the central foothold provided immediately at a front side of the engine compartment and on a central region of the upper frame widthwise of the upper frame; and a maintenance access passage provided on a region which is one of the right and left regions of the upper frame and is a region on an opposite side to the cabin, the maintenance access passage extending rearward while elevated to guide a worker from the ground at a front side of the upper frame to the central foothold, wherein the maintenance access passage has an upper end portion including a most inward edge widthwise of the upper frame, the most inward edge being located inward, widthwise of the upper frame, of an edge which edge is one of opposite edges of the central foothold widthwise of the upper frame and which edge is closer to the maintenance access passage than the other edge, thereby aligning a part of the maintenance access passage and a part of the central foothold in a straight line extending in a front-rear direction to form a transit zone between the maintenance access passage and the central foothold, characterized in that the construction machine further comprising a fuel tank and a hydraulic oil tank provided on the upper frame at respective positions forward of the engine compartment, wherein the fuel tank is located at one of right and left sides while the hydraulic oil tank is located at the other of the right and left sides so as to be opposed to the fuel tank in a right-left direction, wherein a specific tank, which is one of the fuel tank and the hydraulic oil tank and which is a tank located on a right or left side on which side the maintenance access passage is disposed, protrudes upward beyond the central foothold, the central foothold is disposed between the fuel tank and the hydraulic oil tank, and the maintenance access passage is adjacent to the central foothold so as to make the upper end portion of the maintenance access passage approximately flush with the central foothold, at a position forward of the central foothold, to thereby make the transit zone continuous in the front-rear direction. a lower traveling body; and an upper slewing body slewably mounted on the lower traveling body, the upper slewing body including: an upper frame as a base; an engine compartment provided on a rear end region of the upper frame to house an engine and an engine-related device (14, 15, 16); a cabin provided on a front region of the upper frame in one of right and left regions of the upper frame; a central foothold for maintenance work, the central foothold provided immediately at a front side of the engine compartment and on a central region of the upper frame widthwise of the upper frame; and a maintenance access passage provided on a region which is one of the right and left regions of the upper frame and is a region on an opposite side to the cabin, the maintenance access passage extending rearward while elevated to guide a worker from the ground at a front side of the upper frame to the central foothold, wherein the maintenance access passage has an upper end portion including a most inward edge widthwise of the upper frame, the most inward edge being located inward, widthwise of the upper frame, of an edge which edge is one of opposite edges of the central foothold widthwise of the upper frame and which edge is closer to the maintenance access passage than the other edge, thereby aligning a part of the maintenance access passage and a part of the central foothold in a straight line extending in a front-rear direction to form a transit zone between the maintenance access passage and the central foothold, characterized in that the construction machine further comprising a fuel tank and a hydraulic oil tank provided on the upper frame at respective positions forward of the engine compartment, wherein the fuel tank is located at one of right and left sides while the hydraulic oil tank is located at the other of the right and left sides so as to be opposed to the fuel tank in a right-left direction, wherein a specific tank, which is one of the fuel tank and the hydraulic oil tank and which is a tank located on a right or left side on which side the maintenance access passage is disposed, protrudes upward beyond the central foothold, the central foothold is disposed between the fuel tank and the hydraulic oil tank, and the maintenance access passage is adjacent to the central foothold so as to make the upper end portion of the maintenance access passage approximately flush with the central foothold, at a position forward of the central foothold, to thereby make the transit zone continuous in the front-rear direction.