Patent ID: 7866208

Claim:
A flow measuring device, comprising: a flow channel block including: a main flow channel whose both ends are open, and an auxiliary flow channel that branches from the main flow channel; a flow amount measurement element provided for the auxiliary flow channel; and a branch entrance and a collection exit that open in a wall surface of the main flow channel, and that communicate to the auxiliary flow channel, so that a part of a gaseous body that flows through the main flow channel is directed to the auxiliary flow channel through the branch entrance, and the gaseous body that has passed through the auxiliary flow channel is directed back to the main flow channel through the collection exit, wherein a holding member containing portion is provided in a depressed manner for an area excluding an area including the branch entrance and an area including the collection exit in a circumference surface of a space of the flow channel block that configures the main flow channel, an orifice is contained within the main flow channel, an orifice holding member fitted into the holding member containing portion holds the orifice by being brought into contact with the orifice, and the wall surface of the main flow channel is configured by a wall surface excluding the area for which the holding member containing portion is formed out of the main flow channel and an inner surface of the orifice holding member.