The present invention provides a case hardening steel, comprising a component composition including C: 0.10 mass % to 0.35 mass %; Si: 0.01 mass % to 0.50 mass %; Mn: 0.40 mass % to 1.50 mass %; P: 0.02 mass % or less; S: 0.03 mass % or less; Al: 0.04 mass % to 0.10 mass %; Cr: 0.5 mass % to 2.5 mass %; B: 0.0005 mass % to 0.0050 mass %; Nb: 0.003 mass % to 0.080 mass %; Ti: 0.003 mass % or less; N: less than 0.0080 mass %; and balance as Fe and incidental impurities.