A new type of fast neutron spectrometer composed of a proportional counter with methane and a Si semiconductor detector was constructed for the measurement of plasma-temperature. Methane can act as recoil-proton converter and also as energy loss measurement of the proton in the converter. Si detector, off-centered to avoid radiation damage, measures the rest energy of the recoil-proton. The energy resolutions were 2.4 % for 5 MeV neutrons and 2.9 % for 14 MeV neutrons.