To provide a sub-chamber type engine in which no fuel gas is discharged through an exhaust path.

The sub-chamber type engine includes an intake valve 4 provided to an intake path 5 in the main chamber 10, an exhaust valve 6 provided to an exhaust path 7, a sub-chamber fuel gas passage 14 for supplying fuel gas G to a sub-chamber 11, an ignition part 12 for performing spark-ignition of fuel/air mixture formed in the sub-chamber 11, an opening/closing valve 39 capable of interrupting the circulation of the fuel gas G and a check valve 30 provided to a sub-chamber fuel gas passage 14 on a downstream side from the opening/closing valve 39. The check valve 30 is opened when the pressure of the sub-chamber fuel gas passage 14 from the opening/closing valve 39 to the check valve 30 is higher than the pressure of the sub-chamber 11 by a set valve opening pressure or more. The sub-chamber type engine includes an intake valve opening/closing timing adjustment means 51 for closing the intake valve 4 at the timing earlier than a bottom dead center in the intake stroke of the main chamber 10, and an opening/closing valve opening/closing timing adjustment means 40 for opening the opening/closing valve 39 with the start of the intake stroke and closing the opening/closing valve 39 at a timing earlier than a bottom dead center in the intake stroke.

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