To provide medium carbon steel superior in cold forging property and free from cracking, which could not be obtained by conventional technology.

A method for manufacturing steel for cold forging whose hardness after spheroidizing annealing treatment is 83 HRB or less and whose spheroidal carbide proportions in the structure are 70% or more includes a method that repeats a process two or more in a batch type furnace or a continuous furnace as shown in Fig.1 in which medium carbon steel containing, in mass%, C:0.45-0.60%, Si:0.10-0.50%, Mn:0.50-1.20%, Ni:0.30% or less, Cr:0.30% or less, P:0.030% or less, and S:0.030% or less, and made up of remainder Fe and inevitable impurities is heated to the range of Ac1 to Ac1+50°C as the highest-point temperature for the spheroidizing annealing treatment, held for a given length of time, cooled slowly at a cooling speed of 30°C/hr or less in the range of 730-650°C, and cooled further to room temperature.