A fiber body forming method includes a step of defibrating a raw material containing fibers to form a defibrated material; a step of depositing the defibrated material to form a web; a step of applying a liquid containing a thermoplastic resin which binds the fibers to the web; and a step of heating the web to which the liquid is applied to form a fiber body, and in the method described above, the fiber body has a storage elastic modulus of 600 MPa or more at 100° C. and a storage elastic modulus of 400 MPa or more at 150° C.