1.  Field of the Invention
This invention relates to a chair for seating an infant in a posture suitable for shampooing the infant by a bathtub. 
2.  Description of Prior Art
When a mother bathing her infant shampoos him, she cradles him on her lap, holds his head in one hand, and washes his hair with the other hand.  When the infant is no older than one year or so, she has no difficulty because he rarely moves and remains quiet.  When the infant is older than two years, he hates to remain long in one posture, with his head held up in his mother's hand, and soon starts struggling for freedom from his mother's grip.  The mother then finds the work of shampooing difficult.  There are times when the shampoo or the bath water gets into his eyes or ears, things which make him abhor being shampooed. 
To alleviate the situation, there has been proposed an infant's chair for shampooing, so constructed that the back of the infant's neck is supported on the upper end of the back of the chair when he is laid on his back on the chair with his buttocks seated on the bottom thereof and his back stretched over the chair back (Japanese Utility Model Application Disclosure SHO No.  50(1975)-42963). 
The mother finds this chair very convenient because she is now free to use both her hands in washing the infant's head which protrudes from the top of the chair back.  But infants grow fast, and the day soon arrives when not only his head but also his shoulders will protrude from the top of the chair back and, consequently, he will no longer lie stably on the chair.  It is not impossible that when he moves his body suddenly while his mother is busy with the shampooing, the chair will overturn and he will be thrown out onto the floor.  This danger may be avoided by procuring increasingly large chairs to keep pace with his growth.  This practice, however, is unfeasible from the economic point of view.