To provide a circuit board holder, along with a work unit for the circuit board, which holds the circuit board in a mode different from a conventional one.

A plurality of support pins 54 of a support device 42 comprise a first member 62 provided upright on a support stage 52, a second member 64 slidably engaging with the first member 62, and a spring 58 that urges them in the direction away from each other. At attaching an electronic circuit component, both ends of a printed circuit board 14 which has been carried in are restrained by a side part restraining device, and then the support device 42 is raised. So, a support pin 54 corresponding to an electronic circuit component 20 contacts the electronic circuit component 20 or a rear surface 70, and the spring 58 urges the printed circuit board 14 upward. The level of a surface 28 is detected, and rising of the support device 42 is stopped when it comes to a set level. The printed circuit board 14 is supported while deflected upward in convex. An air may be used to urge the first and second members instead of using the spring.