A martensitic heat resistant steel is provided which has improved high temperature creep strength, contains Co and, at a temperature of 600° C. or above, does not form an intermetallic compound substantially having {HEAD ~ a composition} of {TAIL ~ Cr40 Mo20 Co20} W10 C2 Fe 
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A martensitic heat resistant steel is provided which has improved high temperature creep strength , contains Co and , at a temperature of 600 ° C. or above , does not form an intermetallic compound substantially having { HEAD ~ a composition } of { TAIL ~ Cr40 Mo20 Co20 } W10 C2 Fe
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