A catalyst for steam reforming of a hydrocarbon carrying from three to twenty weight percent of nickel as nickel oxide, which is made by immersing alumina particles in a nickel containing solution, drying and then calcining the particles, which alumina particles are of a .alpha.-alumina and of 98 weight percent or more purity and has a pore volume of the pores having a diameter of from 0.1 to 0.5 microns of 0.2 ml/g or more and pore volume of the pores having a diameter of more than 0.5 microns but not more than 10 microns of 0.05 ml/g or more.