A remaining life estimation method for estimating remaining life of high-chromium steel pipe through which high-temperature and high-pressure fluid is allowed to flow, the high-chromium steel pipe formed by integrating base members made of high-chromium steel by welding, the method comprising: an obtaining step (S1) of obtaining a constant (X) indicating a product of a strain rate and a rupture time in Monkman-Grant analysis; a measuring step (S5) of measuring a strain of a surface of the high-chromium steel pipe by measuring a distance between two points on an outer surface of the high-chromium steel pipe , using a sensor mounted to the outer surface of the high-chromium steel pipe on both sides of a welding material sandwiched between said both sides; a recording step (S5c) of recording, at a plurality of times, strain information indicating a strain of the outer surface of the high-chromium steel pipe, in association with time information indicating a measurement time; and an estimating step (S6) of estimating remaining life of the high-chromium steel pipe , from the constant and a plurality of sets of the strain information and the time information, characterized in that said obtaining step (S1) includes obtaining said constant (X) by multiplying a uniaxial rupture ductility (CR) obtained from a specimen of the high-chromium steel pipe , a first coefficient to transform the uniaxial rupture ductility (CR) into multiaxial rupture ductility, a second coefficient to amend consumed life of the specimen , and a third coefficient to amend a measurement pressure into an assessment pressure. an obtaining step (S1) of obtaining a constant (X) indicating a product of a strain rate and a rupture time in Monkman-Grant analysis; a measuring step (S5) of measuring a strain of a surface of the high-chromium steel pipe by measuring a distance between two points on an outer surface of the high-chromium steel pipe , using a sensor mounted to the outer surface of the high-chromium steel pipe on both sides of a welding material sandwiched between said both sides; a recording step (S5c) of recording, at a plurality of times, strain information indicating a strain of the outer surface of the high-chromium steel pipe, in association with time information indicating a measurement time; and an estimating step (S6) of estimating remaining life of the high-chromium steel pipe , from the constant and a plurality of sets of the strain information and the time information, characterized in that said obtaining step (S1) includes obtaining said constant (X) by multiplying a uniaxial rupture ductility (CR) obtained from a specimen of the high-chromium steel pipe , a first coefficient to transform the uniaxial rupture ductility (CR) into multiaxial rupture ductility, a second coefficient to amend consumed life of the specimen , and a third coefficient to amend a measurement pressure into an assessment pressure. a uniaxial rupture ductility (CR) obtained from a specimen of the high-chromium steel pipe , a first coefficient to transform the uniaxial rupture ductility (CR) into multiaxial rupture ductility, a second coefficient to amend consumed life of the specimen , and a third coefficient to amend a measurement pressure into an assessment pressure. <EOS>