A secondary battery includes a cathode; an anode; and an electrolyte between the cathode and the anode, wherein the electrolyte includes a first electrolyte layer including a first polymer, a first lithium salt, and a first particle inorganic material having an average particle diameter (D50) of less than 500 nm; and a second electrolyte layer including a second polymer, a second lithium salt, and a second particle inorganic material having an average particle diameter (D50) of 500 nm or greater, wherein the first electrolyte layer is disposed in a direction facing the anode.