A catalyst, a hydrocarbon steam reforming catalyst, and a method for producing the same are provided. A catalytic metal containing at least Ni is supported on a composite oxide containing R, Zr, and oxygen, at a composition of not less than 10 mol % and not more than 90 mol % of R, not less than 10 mol % and not more than 90 mol % of Zr, and not less than 0 mol % and not more than 20 mol % of M (M: elements other than oxygen, R, and Zr), with respect to the total of the elements other than oxygen being 100 mol %, wherein the composite oxide has a specific surface area of 11 to 90 m2/g, and the largest peak in the wavelength range of 200 to 800 cm−1 of Raman spectrum with a full width at half maximum of 20 to 72 cm−1.