Magnetotellurics method survey has been used for investigation subsurface structures of geothermal field of SeulawahAgam, District of Aceh Besar, Aceh Province. Transfer function of Magnetotellurics data were collected using MTU Unit instrument. We have recorded 2 components of electric fields and 3 components of magnetic fields in the range of frequency from 10-5 to 1 kHz. 5 stations with spacing varied from 2 to 10 km were measured along a profile with length of 30 km. The profile crosses

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... awahAgam volcano in south-north direction. Apparent resistivity and phase data of TE mode were included for 2-D inversion modeling using the MT2DInvMatlab code. The inverted model shows well distribution of electrical conductivity associated as hydrothermal structure. At the depth of 200-800 m there is a conductive layer (ρ < 10 Ωm) predicted as cap rock structure and at the depth of 1-4 km there is a hydrothermal reservoir indicated by resistivity values 100-1000 Ωm..