An optical waveguide for a touch panel and a touch panel using the same. A lens portion 30 formed in an end portion of each light-emitting core 3 and each light-receiving core 3 has a tapered portion 31 such that the width thereof gradually increases toward an end surface thereof. The end surface is an arcuately curved surface 32 which bulges outwardly and has a radius of curvature R. When the tapered portion 31 has a length L not less than 800 μm, a taper angle α is in the range of 2 to 20 degrees, and (A) is satisfied. When the tapered portion 31 has a length L not less than 400 μm but less than 800 μm, the taper angle α is in the range of 4 to 16 degrees, and condition (A) is satisfied. 0.5×L×tan(α/2)