A reinforcing structure for a vehicle body front part has a reinforcing member 10 disposed at a corner portion 9 formed by a dash panel 5 and a dash side panel 6. The reinforcing member 10 includes a plate-like main body portion 11 that has a width in a horizontal direction and extends between the dash panel 5 and the dash side panel 6 near the corner portion 9, a first connection portion 12 that is provided at a first end portion 11a of the main body portion 11 and extends in a vehicle vertical direction, and a second connection potion 13 that is provided at a second end portion 11b of the main body portion 11 and extends in the vehicle vertical direction. The dash panel 5 and the first connection portion 12 of the reinforcing member 10 are connected to each other by welding, and the dash side panel 6 and the second connection portion 13 of the reinforcing member 10 are connected to each other by welding.