"They are appealing to people's nurturing instincts."
However, Prof Dautenhahn, said it was "offensive" to believe it could be a child substitute for women without children, as some reportshave suggested.
Some of Toyota's marketing material shows women cradling the robot, but the company does not not explicitly make this claim.
"It might make people feel good, but there is no human component here, robots cannot be substitutes for children," said Prof Dautenhahn.
'Casual conversation'
Toyota says Kirobo Mini can:
engage in "casual conversation", using gestures, facial expressions and blinking
remember user preferences and previous events, such as likes, dislikes and outings
use data from connected devices such as those in the home or car to generate comments
It has a provisional price tag of 39,800 yen (£300), and there are no plans to sell it outside of Japan.
It is considerably cheaper than other companion robots - Aldebaran's humanoid robot, Pepper, cost 198,000 yen at launch.
Kirobo Mini's predecessor, a 34cm robot called Kirobo, was sent up to the International Space Station in 2013.
Its job was to accompany Japanese astronaut Kochi Wakata as part of a study about isolation.