Long fiber reinforced thermosetting resins are required in automotive industry because they are effective for weight reduction and heat resistance of automobiles. Compared with thermoplastic resins, it is difficult to mold thermosets since degree of curing and the resin viscosity are influenced by crosslinking reaction. Both the molding temperature and the molding time are closely related to the crosslinking reaction. Therefore, the molding machine which can change the molding temperature in a short time is required to increase the proportion of thermosets in automobiles. In this study, the injection molding machine for long fiber reinforced thermosets using induction heating (IH) was developed, and the effect of the molding process on mechanical properties of a product was investigated. In the injection molding machine, there is no nozzle at the top of the barrel to prevent resins from curing. The barrel temperature rises by 170 ° C in 5 seconds by IH. Thus, the resin viscosity is lowered before curing, and it is capable of kneading resins with less fiber breakage. In addition, the barrel temperature decreases by air cooling to prevent thermosets from curing. Long glass fiber reinforced phenolic resin and short glass fiber reinforced phenolic resin were used to investigate the effect of fiber length. Measurement of residual fiber length, bending tests and impact tests were conducted, and the influence of the molding process on bending and impact properties was investigated. As a result of the experiments, products of long fiber reinforced phenolic resin were continuously molded within 2 minutes 30 seconds, and the mechanical properties, especially impact strength were better than short fiber reinforced phenolic resin. From these results, the injection machine using IH has a potential to greatly contribute to metal substitution with plastics.