A blow-by gas device of a supercharger-equipped engine, the blow-by gas device including a supercharger in a portion downstream of a throttle valve in an intake passage , the blow-by gas device comprising: a PCV valve ; and a blow-by gas passage connected to a portion of the intake passage located between the throttle valve and the supercharger and to an engine body , the blow-by gas passage introducing blow-by gas discharged from the engine body into the intake passage via the PCV valve , wherein the supercharger includes a supercharger body including therein a rotor chamber , a rotation shaft rotatably supported on at least one bearing part communicating with the rotor chamber , the rotation shaft being rotatable by power of a driving source, and a supercharger rotor provided integrally with the rotation shaft and rotatably disposed inside the rotor chamber , the supercharger body includes a space portion communicating with the bearing part , the space portion is connected to a communication passage , and the communication passage guides the blow-by gas discharged from the engine body to the space portion , characterized in that the supercharger body includes an intake-side space portion communicating with the bearing part on an intake side and a discharge-side space portion communicating with the bearing part on a discharge side, the intake-side space portion is connected to a first communication passage communicating with a portion upstream of the PCV valve in the blow-by gas passage or with the engine body , and the discharge-side space portion is connected to a second communication passage branching off from a portion downstream of the PCV valve in the blow-by gas passage . a PCV valve ; and a blow-by gas passage connected to a portion of the intake passage located between the throttle valve and the supercharger and to an engine body , the blow-by gas passage introducing blow-by gas discharged from the engine body into the intake passage via the PCV valve , wherein the supercharger includes a supercharger body including therein a rotor chamber , a rotation shaft rotatably supported on at least one bearing part communicating with the rotor chamber , the rotation shaft being rotatable by power of a driving source, and a supercharger rotor provided integrally with the rotation shaft and rotatably disposed inside the rotor chamber , the supercharger body includes a space portion communicating with the bearing part , the space portion is connected to a communication passage , and the communication passage guides the blow-by gas discharged from the engine body to the space portion , characterized in that the supercharger body includes an intake-side space portion communicating with the bearing part on an intake side and a discharge-side space portion communicating with the bearing part on a discharge side, the intake-side space portion is connected to a first communication passage communicating with a portion upstream of the PCV valve in the blow-by gas passage or with the engine body , and the discharge-side space portion is connected to a second communication passage branching off from a portion downstream of the PCV valve in the blow-by gas passage . <EOS>