An injection apparatus including a flow path switching block, the injection apparatus comprising: a plasticization device configured to melt resin; at least one plunger injection device (4, 5) configured to measure an amount of resin melted in the plasticization device and to inject the melted resin; an injecting portion configured to inject the resin; and the flow path switching block connecting the plasticization device, the plunger injection devices (4, 5) and the injecting portion, wherein the flow path switching block comprises a first connecting flow path, a second connecting flow path, a third connecting flow path, a fourth connecting flow path and one flow path switching valve, wherein the plasticization device is connected to the first connecting flow path, a first plunger injection device is connected to the second connecting flow path, the injecting portion is connected to the third connecting flow path, and a second plunger injection device is connected to the fourth connecting flow path, wherein when the flow path switching valve is switched to a first position, the first connecting flow path and the second connecting flow path communicate with each other, and the third connecting flow path and the fourth connecting flow path communicate with each other, wherein when the flow path switching valve is switched to a second position, the first connecting flow path and the fourth connecting flow path communicate with each other, and the second connecting flow path and the third connecting flow path communicate with each other, and wherein the second connecting flow path is configured to receive a distal end portion of a plunger of the first plunger injection device at the time of injection, characterized in that the distal end portion of the plunger of the first plunger injection device is configured to enter a position where the distal end portion reaches a valve body of a moving portion of the flow path switching valve, and the flow path switching valve comprises exactly two independent in-valve flow paths: a first in-valve flow path and a second in-valve flow path, the first and second in-valve flow paths (25, 26) being rotated within the flow path switching block to be switched to the first and second positions. a plasticization device configured to melt resin; at least one plunger injection device (4, 5) configured to measure an amount of resin melted in the plasticization device and to inject the melted resin; an injecting portion configured to inject the resin; and the flow path switching block connecting the plasticization device, the plunger injection devices (4, 5) and the injecting portion, wherein the flow path switching block comprises a first connecting flow path, a second connecting flow path, a third connecting flow path, a fourth connecting flow path and one flow path switching valve, wherein the plasticization device is connected to the first connecting flow path, a first plunger injection device is connected to the second connecting flow path, the injecting portion is connected to the third connecting flow path, and a second plunger injection device is connected to the fourth connecting flow path, wherein when the flow path switching valve is switched to a first position, the first connecting flow path and the second connecting flow path communicate with each other, and the third connecting flow path and the fourth connecting flow path communicate with each other, wherein when the flow path switching valve is switched to a second position, the first connecting flow path and the fourth connecting flow path communicate with each other, and the second connecting flow path and the third connecting flow path communicate with each other, and wherein the second connecting flow path is configured to receive a distal end portion of a plunger of the first plunger injection device at the time of injection, characterized in that the distal end portion of the plunger of the first plunger injection device is configured to enter a position where the distal end portion reaches a valve body of a moving portion of the flow path switching valve, and the flow path switching valve comprises exactly two independent in-valve flow paths: a first in-valve flow path and a second in-valve flow path, the first and second in-valve flow paths (25, 26) being rotated within the flow path switching block to be switched to the first and second positions.