A transistor circuit of low shutoff-state current includes: a first transistor, a transistor string, and a switch. The first transistor and the transistor string are connected in series. The switch is configured to shut off the circuit. The first transistor is configured to reduce the shutoff-state current flowing therethrough using the negative feedback effect of the transistor string when the circuit is in a shutoff state; and the transistor string is configured to reduce the shutoff-state current flowing therethrough using a negative gate-source electrode voltage difference thereof and the bulk effect of the transistor.